Martin Cagan, Silicon Valley Product Group
The PRD describes the product your company will build. It drives the efforts of the entire product team and the company’s sales, marketing and customer support efforts. It’s hard to come up with a more important, higher leverage piece of work for a company.
The purpose of the product requirements document (PRD) or product spec is to clearly and unambiguously articulate the product’s purpose, features, functionality, and behavior. The product team will use this specification to actually build and test the product, so it needs to be complete enough to provide them the information they need to do their jobs.
If the PRD is done well, it still might not be a successful product, but it is certain that if the PRD is not done well, it is nearly impossible for a good product to result.
The PRD versus the MRD
We draw a distinction here between the product requirements and the market requirements (often referred to as the “MRD”). Put very simply, the market requirements describe the opportunity or the market need, and the product requirements describe a product that addresses that opportunity or need.
The PRD versus the Product Strategy and Roadmap
The product strategy describes a vision, typically between two and five years out, of where you want the product to go, and the product roadmap describes the various steps to get there. The PRD describes a particular product release along that path.
TEN STEPS TO A GOOD PRD
The purpose of this paper is to describe a proven, repeatable process to create a good PRD. The ten steps described here are not easy, but they can help you produce a strong PRD. The amount of time this process takes depends greatly on the size and complexity of your product, and how prepared you are in terms of the knowledge and skills required.
Step 1: Do Your Homework
Your goal with the PRD is to come up with a compelling product. In order to do this, you must do your homework. This means studying your customers, your competitors, and your team’s capabilities, including available technologies.
This begins with customers, users, competitors, industry analysts, your product team, your sales force, marketing, company executives, other employees – anyone that has insight into the problem and possible solutions.
There is much more to the process of preparing, and this is discussed in detail in the paper “Behind Every Great Product” also available from the Silicon Valley Product Group.
Realize also that a significant factor in your ability to convince the team of the eventual success of the product is the degree of confidence you project, and you will be more confident and more convincing if you’ve done your homework well.
Step 2: Define the Product’s Purpose
Every good product starts with a need that it is trying to fill. You must have a clear understanding of that need, and how your product addresses that need.
It is essential that the product manager establish a very clear, concise value proposition that lets her easily communicate to everyone -the product team members, company executives, customers, the sales force-what the point of this product really is.
While this sounds obvious, few products have such a clear value proposition. Consider the “elevator pitch” test. If you had a chance to ride the elevator with the CEO of your company, and she asked what the point of your product was, could you answer that question before the ride is up? If not, you have work to do.
It may be that the product does not have focus; it may be trying to do so many things that nothing clearly stands out. It may be that what you think is the big thing is just not resonating with customers. It could be that your product is trying to solve a non- problem; maybe you have a technology that you’re still trying to find an application for.
The value proposition should also make clear how this product helps deliver on the product strategy. Note that you do not need to talk about every little feature; in terms of a clear value proposition, less is truly more.
The product requirements need to specify exactly what the objectives of this specific product release is, and how they will be measured. The objectives should also be prioritized.
For example, your objectives may be: 1) ease of use, 2) retail price under $100, and 3) compatibility with previous release. You could then go on to elaborate on how you will measure these objectives. For items like a specific retail price, it is straight- forward. For items like “ease of use,” you need to be specific as to what level of usability the product requires. This is typically defined in terms of the target user. Usability engineers can rate the usability of your product for a given type of user. They can also rate the severity of usability issues, and you may specify that there will be no major usability issues.
The key is to be very clear to everyone involved just what success looks like, and to provide the guidance that the product team needs in order to make the necessary trade-offs in design and implementation.
Step 3: Define the User Profiles, Goals and Tasks
Now that you understand what problem you want to solve, the next step begins with an in-depth understanding of the target users and customer. During this step, it is important to work very closely with your product designer.
By this stage, the product manager will have hopefully met with many target customers, and have spent considerable time with first-hand observations and discussions. Now we need to classify the types of users and customers, and to determine who the primary users are.
For example, if you’re building an Internet auction service such as eBay, you know that you have both buyers and sellers, and for each of those you have low-volume/occasional users and high-volume/frequent users. It is not hard to imagine that there are several other less prevalent types of users as well, such as the corporate purchasing agents that may buy items for their company.
What the product manager and designer need to do is first identify the most important constituencies, and then try to characterize them in considerable detail, so that you can use these profiles to guide you in the design of the product. These profiles are sometimes called “personas” and while they should be fictitious, they should be as representative, realistic and plausible as you can make them. The idea is to come up with an archetype which captures the essence of this type of customer.
Here’s an example:
Leon the Power Seller is a 46 year old male that lives in Fresno and runs a small motorcycle parts business. While he does maintain a small shop, almost all of his sales come from eBay, where he sells on average 400 items per month. He sells a wide range of motorcycle related items, but his most popular items are saddle bags for Harley Davidson’s. He owns two big Harley’s himself, and he also drives a 1993 Toyota Pickup. Leon is married and has two teenage sons.
Leon bought his computer just so that he could use eBay, and seldom uses anything except eBay and e-mail. Leon has been selling on eBay for three years now, and has learned what he needed to in order to effectively sell. He has a feedback rating of over 5000, which he takes great pride in. When eBay changes things on the site, especially the selling process, it can be very aggravating for him to learn the differences and change his procedures.
Leon has well-established routines where he lists items to sell on Monday, and most of his auctions end by Friday, and he tries to get the shipments out within a few hours of receiving the payments.
Hopefully this description helps you get to know Leon and understand where he is coming from. As we consider new features, we can ask ourselves what Leon’s response to the feature would likely be, and what we would need to do in order to get him successfully utilizing it.
Narrowing the set of profiles down to just the key ones is essential. Trying to please everyone is futile, and typically ends up pleasing no one, so it is important to try and come up with the few most important and prevalent profiles. Similarly, if you do not try and precisely characterize your target user, you will have this abstract notion and find it difficult to understand how your customers will react. You’ll tend to assume that your customer is more like you than he really is.
Once we have identified and characterized our main types of users, we then need to identify what each user’s main goals or objectives are in using this product. This may sound simple, but it can often be challenging to untangle the underlying problem to be solved, when all around you people are telling you essentially the solution they think they want.
Everyone from the CEO to sales reps to engineers to customers are all too happy to “help” you come up with the solution. They’ll tell you that you need to add a button or a shortcut in a particular place, or add a specific feature because a competitor has it, or change the colors because they don’t like it.
The problem with jumping right to the solution is that there are often much better ways of solving a problem that the product manager and designer can come up with, if they are given the time and the freedom to come up with alternative solutions.
The best solution hinges on having a clear understanding of just what problem needs to be solved. The objectives may be different for each user profile, so it is important to be able to look at the objectives in terms of the profile they relate to. It is very possible that the feature being requested addresses a problem that is not one of the objectives of the primary user profiles.
With the user profiles and their associated goals in hand, we can now move on to designing the tasks that help these people accomplish their goals. This is the heart of the product specification process, and is the place where creativity and innovation are to be encouraged and facilitated as much as possible.
Many outstanding products simply solve an existing problem in a new and better way. Sometimes this comes from the application of new technology, but mostly it comes from an insight that leads to a new approach.
For example, TiVo took the old problem of recording TV shows and came up with an entirely new approach that let customers accomplish their objectives much more easily, and established an entirely new category of electronics device.
Notice that we have talked about goals and tasks, but that we have not mentioned features. This is because features should be in support of required tasks that map to customer objectives. You will often find that many features either map to very low priority goals, or are simply extra functionality.
There are good reasons to eliminate any functionality you can in the name of making the required functionality more accessible. Ironically, the fewer features you have, the more powerful your product is often perceived. This is because the less features you have, the more features that your customers will actually discover and use, and the more they can successfully use, the more powerful they will perceive your product. The reason this is so counterintuitive is that most of us are not anything like our target customers, and we are willing to spend far more time exploring features and tolerating complexity than customers not in our industry.
Step 4: Define your Product Principles
By now you should be formulating some detailed ideas on your requirements and the user experience. You will, however, still be faced with countless decisions and trade- offs, and it is important that you have some criteria in which to make the best decisions for your product.
In most teams, each product team member has some ideas in their head in terms of good principles for the product, but rarely do two people have the same ideas, and these differences can lead to unpleasant surprises later.
It is very valuable to try and identify a set of product principles that will guide the entire team throughout the project. These principles will be specific to your domain and your particular project.
As an example, consider TiVo. When the team began on the product effort, the following product principles were established and shared across the team:
It’s entertainment, stupid
It’s TV, stupid
It’s video, damnit
Everything is smooth and gentle No modality or deep hierarchy Respect the viewer’s privacy
It’s a robust appliance, like a TV
These principles impacted the product definition greatly, and in many cases made for a much more difficult implementation, but arguably they are the source of the product’s success.
Similarly, at eBay the mantra was: 1) easy to use; 2) safe; and 3) fun.
You can see how product objectives like these can provide a constant compass for the entire product team in the many decisions they must face during the course of the project.
Step 5: Prototype and Test the Product Concept
This is the stage where you actually come up with your product ideas. This is where you want to be as creative and innovative as possible.
One of the biggest and most common mistakes product teams make is to have far more confidence in their product specifications than they should, and they move forward and think they’ll adjust the product, if necessary, once they get beta feedback. But of course beta is not the time for major changes, and hence no wonder so many first product releases are so far from the mark.
For most products, however, you can do a very significant amount of product validation testing at this stage, using various forms of prototypes.
First, it’s important to consider carefully each of the three forms of testing you will likely need to do:
One immediate question is whether or not the product is going to be possible to build. Your engineers and architects should be very involved in investigating technologies and exploring possible approaches. Some paths will be dead-ends, but hopefully others will prove viable.
What is most important is that if there are obstacles the engineering team considers insurmountable in this product’s timeframe, it is important to know this now rather than discovering this much later in the process.
Your designers (product designers) will be working very closely with you to come up with ways of presenting the functionality in the product so that the different types of users can figure out how to actually use the product.
Usability testing will often uncover missing product requirements, and also, if done well, identify product requirements that are not as necessary as originally thought. You should plan on multiple iterations before you come up with a successful user experience.
The purpose of the usability prototype is to have something to test on real people, and usability testing is the art and science of getting quality feedback on your product from your target customers. Certainly the product manager and designer will use the prototype and learn a great deal from it, but there is no substitute for putting the prototype in front of actual people from the target customer base.
Product Concept Testing
Finally, it is not enough to know that your product is feasible to build and will be usable, but what really matters is whether or not your product is something users will want to buy – i.e. how much do they like and value what you’re doing? This testing can typically be combined with the usability testing.
For a few small product efforts, simply working your ideas out on paper is sufficient. But for most products, with complex user interactions or new uses of technology, a prototype of some form is absolutely critical in order to assess whether or not the product will meet the product objectives.
The prototype may be a physical device, or it may be a quickly assembled version of a software product. The key is that it needs to be realistic enough that you can test the prototype on actual target customers and they can give you quality feedback.
In the past, there were two major obstacles to prototyping. The lack of good prototyping tools meant that it could take a long time to actually construct the prototype. Another problem was in unaware management not understanding the difference between the implementation of a prototype and the real product, and the teams would get pressured to use the prototype as the basis for the final product, with predictable bad results in the implementation.
Today, there are outstanding prototyping tools that can let engineers or designers rapidly create very functional prototypes that can effectively emulate the future product, to the degree necessary, and form the basis of realistic user testing.
Moreover, most managers today understand that building a simulation and building the actual product are very different – akin to building a scale model of a house, and building the actual home.
It is impossible to emphasize enough how valuable it is to validate your product concept before you go and actually build the product. Once the real engineering begins it becomes very difficult to make significant changes and the costs of the changes rises dramatically.
Step 6: Identify and Question Your Assumptions
Once you think you understand the problem you want to solve, now is the time to start identifying and questioning your assumptions. It is very easy to make assumptions and not even be aware of them. Make sure you don’t specify a candle in the PRD and prevent yourself from getting a light bulb.
Astronomy was originally defined as the study of how the sun and the planets revolve around the earth. Its very definition had an assumption that prevented anyone from getting the right answer.
Step 7: Write It Down
You’ll need to get all this down of course. Most PRD’s are Word documents, but some are Wiki sites, some are PowerPoint decks, and some live on whiteboards. The media and format are far less important than the content. Although what is critical is that the PRD be something that the entire team can easily access, it won’t get lost, and that the PRD needs to be in a form that can be updated throughout the project.
Remember that a conversation is between two people. The PRD communicates to the entire product team.
It is also important to keep in mind that as important as the PRD is, what really matters is the product that gets shipped. Nothing is more important than that. So don’t worry about how pretty your PRD looks or how thick it is. So long as it’s readable and understandable, it is the content that matters.
The PRD is comprised of four major areas.
Your job is to paint the target. The team needs to know what they are aiming at, and that target needs to be described as clearly as possible. Make sure your description covers:
The problems you want to solve, not the solution
Who is the product for? Companies, Customers, Users Details are great, but the big picture must be clear.
Remember that while brainstorming sessions and oral instructions and discussions lead to better written requirements, they will be lost if they don’t get into the PRD.
The body of the product requirements specification will of course be the requirements themselves. The specifics of the requirements will entirely depend on your domain, but regardless of your industry, your product team will benefit from clear, unambiguous requirements that state the need, rather than the solution.
Describe each feature at the level of the interaction design and use cases. You must be very clear what each feature is and what the user experience should be, while leaving as much flexibility to the engineering team as possible.
It is also important to identify which of your requirements are in support of each objective. This is part of the discipline referred to as “requirements traceability” and for mission critical products this is often a formal process. But every product specification can benefit from clearly identifying exactly which requirements support which product objective. If someone decides to cut a requirement, it can be difficult to understand the full impact of this cut. The mapping from requirements to objectives helps make this clear.
The release criteria are often just hand-waved, but a good PRD puts considerable thought into what the true minimum requirements are, for each of the release criteria, which typically includes:
One of the most difficult sections is to describe the timeframe that the product is needed. It is not useful just to list a random date, but rather you should describe the context and motivation for the timeframe, and describe a target window.
You want the entire team to be as motivated as you are to hit that target window, with the right product for the market.
Step 8: Prioritize
Beyond clear requirements, it is important to prioritize and rank-order every one of your requirements. Most product managers, if they prioritize at all, simply indicate whether a requirement is “must-have,” “high-want” or “nice-to-have” (or some comparable classification system).
The classification is important and must not be taken lightly. The product manager should have an extremely high bar for anything flagged as “must-have.” This literally means that the product should not ship if even one of the “must-have” features is not ready. So extreme care should be used for any feature marked “must-have” and these features should map directly to the core value proposition of the product.
The “high-want” features are important, and you do want all of these in the product before shipping if at all possible, but you are not willing to delay the product for these features.
The “nice-to-have” features are useful for the product team to be aware of, even if most of them do not get built until a future release, at least the product can be architected to handle these features, where appropriate, in the future.
While the classification of requirements is necessary, this is not sufficient. Within each prioritization classification it is important to rank-order each requirement, from 1 to n. There are a couple reasons for this.
First, time to market is always a concern, and schedules often slip, and you may well be forced to cut some features in order to get to market. You do not want the product team to implement the easy features first, and end up with several not so important features ready to go, yet customer-critical features on the chopping block.
Second, during the design and implementation phase, the team will learn a great deal as issues arise and are resolved, and it is very possible that you will identify additional critically important features to be added. The prioritization helps you to know what to cut in order to accommodate more important features.
The point is that if the product manager does not prioritize and rank-order the features in terms of their importance in creating a successful product, then other less relevant factors will influence what gets built in what order.
The entire PRD process should be a continuous refinement and sharpening of your thinking. Sharp thinking equals sustainable vision. Fuzzy thinking equals failed product. It is much easier to decide now than in the heat of the battle, and it also helps engineering come up with a development plan. Recognize that time may change the priorities, which is fine, just be sure to make the change in the PRD.
Step 9: Test Completeness
Now that you have a draft of the full PRD, you will need to test the PRD for completeness. Can an engineer get enough understanding of the target in order to get the product there? Can the QA team get enough information to design a test plan and begin writing their test cases?
Once the stakeholders have all reviewed the PRD and identified any areas that need additional details or clarification, and you have addressed these issues, you now have a PRD to build a product from.
Step 10: Managing the Product
During the course of implementing the product, there will be countless questions identified, even with the best of PRD’s. Resolve all questions about requirements by pointing people to the PRD. If it’s not in the PRD, put it in the PRD. Your job is to quickly resolve all the questions and issues, and to record these decisions in the PRD.
If you’ve done your job and kept the PRD accurate, any project reviews that come up should be very easy to prepare for by just selecting from the appropriate sections of the PRD.
Remember that the PRD is a living document, and you should track all features in the PRD through product launch.
Finally, you may find that you need additional topics covered in the PRD. If you believe something additional is required in order to meet your objectives in the PRD then by all means include it.