In part three of A Comprehensive Guide To Product Design, I’ll cover design (validating ideas, prototyping, handoff), testing, and validation (testing with product team and real users), and post-launch activities (understanding how users interact with your product and testing changes in design).

Validate ideas

There are two types of ideas — good ideas that lead to product success, and bad ideas that can lead to failure. Of course, design execution is important, but the idea itself plays a crucial role in the process. A well-executed bad idea is a big waste of time and energy. It’s critical to reveal bad ideas as early as possible. So, how do you distinguish a good idea from a bad one? A technique called a design sprint can help you with that.

Design sprint

A design sprint is a five-day design framework for validating ideas and solving challenges. It enables product teams to build a prototype that they can put in front of users to validate the initial design hypothesis (to see if it solves the problem for the user).

Design sprints are a process of quickly creating a product’s future state, be it a website or app, and validating it with a group of users, stakeholders, developers, and other designers. This whole concept is based on the idea that, by a design team setting a direction and iterating rapidly, it’s possible to design a product that presents the maximum value for people who will use it.

Circular process diagram showing ideas to build to launch to learn.
Design sprint. Image by Google Ventures.


  • Don’t get stuck with the first solution that comes to mind. In most cases, your first ideas won’t be good enough, because at the early stage of ideation, you won’t yet have a good understanding of the problem you’re trying to solve. Generate as many different designs as possible instead of focusing solely on your first solution.


After the ideation phase, the product team should have a clear understanding of what they want to build. During the design phase, the product team will begin to create the solution to solve the client’s problem and implement concepts.


To deliver a good user experience, prototyping must be a part of your design process. A prototype is an experimental model of an idea that enables you to test it before building the full solution. A prototype often starts small, with you designing a few core parts of a product (such as key user flows) and grows in breadth and depth over multiple iterations as required areas are built out. The finalized version of a prototype is handed off for development.

When it comes to prototyping, efficiency is vital. One of the most efficient prototyping processes is rapid prototyping. The process of rapid prototyping can be presented as a cycle with three stages:

  1. Prototyping. Creating a solution that can be reviewed and tested.
  2. Reviewing. Giving your prototype to users and stakeholders and gathering feedback that helps you understand what’s working well and what isn’t.
  3. Refining. Based on feedback, identify areas that need to be refined or clarified. The list of refinements will form the scope of work for your next design iteration.
 Circular process diagram that shows Prototype to Review to Refine and iterate
The rapid prototyping process — prototype, review, refine.

Prototypes range from rough sketches on a piece of paper (low-fidelity prototypes) to interactive simulations that look and function like a real product (high-fidelity prototypes). Depending on the stage of the design process and the goals of the prototype, you’ll need to select the appropriate prototyping technique. It’s crucial to choose the method of prototyping that minimizes work and maximizes learning.

Paper prototyping

A lot of digital prototyping tools today help us to create prototypes with the least possible amount of effort, but sketching on a paper still remains the most important tool for any designer. That’s because sketching allows designers to quickly explore a lot of different design alternatives without investing much time and energy in each one. It forces designers to concentrate on the essence of a product’s design (what it does), rather than its aesthetics (how it looks). And what’s especially great about sketching is that it opens up design to everyone — anyone can sketch, and no special tools are required. The fact that anyone can participate in the design process makes sketching an ideal tool during brainstorming sessions.

 Man touching paper which shows mock application layout
A common practice for testing paper prototypes is to have one person play “computer,” switching the sketches around according to user choices. Image by UX Playground.


  • Paper prototyping allows for rapid experimentation. Different user interface elements can be drawn, cut out, copied to make extras, and then assembled on a new piece of paper.

Digital prototyping

With paper prototyping, explaining complex interactions in words can be tough. When a designer needs to explain a complex design detail, such as an animation to a developer or wants to run a user research session to validate a design, they usually use a digital interactive prototype.

Digital prototyping is the process of creating an interactive design that other people can experience themselves. Just a decade ago, in order to build a high-fidelity prototype, you actually had to code the solution using programming language. These days, prototyping tools allow non-technical designers to create high-fidelity prototypes that simulate the functionality of a final product in just a few clicks.

 Gif of navigating a mobile travel application
Prototyping in Adobe XD. Digital prototypes are well suited to defining dynamic on-page interactions, such as expanding content and animations.


  • Avoid dummy text. Dummy text, like lorem ipsum, should be avoided in early stages of digital prototyping. Use real content to understand how it affects the overall design.
  • Use digital prototypes as an up-to-date specification for developers. Prototyping tools such as Adobe XD allow you to spit out specification documentation in just a few clicks. It’s an always up-to-date specification available to developers.
 Gif showing using Adobe XD application to create a web experience
Adobe XD allows you to inspect text properties, copy character styles and content, and view measurements.

At the end of the prototyping phase, the design will be ready for production. It’s the time when the designer hands over the design to a developer for coding. During the developer handoff, a designer must clearly communicate to the developer how every piece of the design looks and works. Multiple layers of information and detail need to be conveyed, and it’s critical for designers and developers to be on the same page.

Design specification

Design specs are detailed documents that provide information about a product, such as user interface design details (colors, character styles, and measurements) and information (flows, behaviors, and functionality). A developer uses this document to take the design into production and build the product to the designer’s specifications.

Read Design Specifications: Speeding Up the Design to Development Workflow and Improving Productivity for more information about design specifications.

Testing and validation

The testing and validation phase helps a product team ensure the design concept works as intended. Product testing is an art in itself. Do it wrong and you’ll learn nothing. Do it right and you might get incredible, unexpected insights that might even change your product strategy.

Usually, the validation phase starts when the high-fidelity design is fleshed out. Similar to the product research phase, this phase also varies between projects.

Testing with the product team

It’s possible to conduct limited testing for the product using resources you already have — your team.


“Eating your own dog food” is a popular technique of testing. Once the design team has iterated on the product to the point where it’s usable, testing it in-house is a great way to find the most critical issues.


  • Practice dogfooding to develop empathy among your team.

Testing with real users

Usability testing

According to the Nielsen Norman Group, if you want to select just one type of user research for your project, it should be qualitative usability testing. The basic idea behind a usability test is to check whether the design of a product works well with the target users. It’s relatively easy to test a concept with representative users. Once an interactive version of a product idea is in the hands of real users, a product team will be able to see how the target audience uses the product. The primary goal of this user experience testing method is to identify usability problems, collect qualitative data, and determine the participants’ overall satisfaction with the product. Gathering and analyzing verbal and non-verbal feedback from the user helps a product team create a better user experience.

Usability testing is often done formally (where a researcher creates a screener, hires participants, has them come into the lab environment, records the session, etc.).

 Photo of usability testing being conducted
In formal usability testing, you recruit some test participants and give them a set of scenarios that lead to usage of specific aspects of a product (or prototype).

Usability testing can also be done informally — in the format of guerrilla testing. With guerrilla testing, a product tester goes to the nearest coffee shop, finds participants, asks them to play with a product for 10 minutes, and then gives them a small treat as a thank you.

 Photo of man holding up sign that reads
Informal guerilla usability testing. Image by johnferrigan.


  • You don’t need a lot of test participants. According to Jakob Nielsen’s research, up to 85 percent of core usability problems can be found by observing just five people using the product.

Read the article Simple Tips to Improve User Testing for more information on usability testing.

Diary study

A diary study can be used to see how users interact with a product over an extended period of time (ranging from a few days to even a month or longer). During this period, study participants are asked to keep a diary and to log specific information about their activities. Usually, the diary includes open-ended questions such as:

  • Where were you when using the product?
  • What tasks did you hope to achieve?
  • Did something frustrate you?

A diary study helps a researcher find answers to questions like:

  • What are users’ primary tasks?
  • What are their workflows for completing complex tasks?

The answers provide organic behavioral insights and help develop a rich understanding of a participant’s context and environment.

 Photo of filling out task checklist diary
In-situ logging is the most straightforward method to collect data from diaries. Participants are asked to report all important information about relevant activities as they complete them.


  • Create clear and detailed instructions for logging. Be as specific as possible about what information you need participants to log.
  • Remind study participants about logging. Prompt participants to fill in their diary (for example, through a daily notification).
  • Make it possible to add screenshots to a diary. If you use a digital version of a diary, make it possible for participants to upload screenshots. Screenshots are a nice supplement for user data and will help you with future data analysis.

Post-launch activities

Just because a product officially launches doesn’t mean the product design is over. In fact, product design is an ongoing process that continues for as long as a product’s in use. The team will learn and improve the product.

Understand how users interact with the product

Metrics analysis

You need to know how users are using your product out in the wild  —  and that’s where analytics come in. Numbers provided by an analytics tool (clicks, navigation time, bounce rates, search queries, etc.) can be used to understand how people are actually using your product. Metrics can also uncover unexpected behaviors that are not explicit in user tests. Product team must continually track product performance to see if it meets customer satisfaction and if any improvements can be made.

 Photo of data dashboard showing pie chart, map of world and trend line chart
Good design has to be informed by the data, and if you learn to use it right, you will get enormous improvements in your work. Image by Ramotion.


  • Use analytical tools. Powerful tools such as Google Analytics and Hotjar can be used to understand user behaviors.
  • Don’t rely solely on analytics. You can’t determine the effectiveness of a product’s design based solely on analytics. To validate the analytical insights, you should conduct further hallway tests.

Feedback from users

The best way to avoid having to rework a product is to inject feedback into the process. Regular user feedback (in the form of online surveys or analysis of customer support tickets) should be at the heart of the product design process. This information will drive product refinement.


  • Don’t make it hard for users to provide feedback. Don’t hide the “Leave feedback” option. Make it easy and, if possible, rewarding for users to share their feelings and ideas about your product.

Testing changes in design

A/B testing

An A/B test is an appropriate testing method when designers are struggling to choose between two competing elements. This testing method consists of showing one of two versions randomly to an equal number of users and then reviewing analytics to see which version accomplished the specific goal more efficiently.


  • Get into the habit of A/B testing your design changes. Knowing that all of your changes will be A/B tested will give you a tremendous amount of freedom to try new (and potentially risky) things. You won’t have to worry that some change you’ve made will ruin everything.

Four essential things to remember about product design

1. The process should morph to fit the project

When it comes to product design process, there’s no one-size-fits-all solution. The process employed should be tailored to fit the project’s particular needs, both business and functional. Here are just a few factors that can affect the design process:

  • Customer’s needs or preferences.
  • How much time you have (the project’s deadline).
  • Project’s budget (for example, a limited budget won’t allow you to conduct a lot of interviews).

A process tailored to the capabilities of the business and of users is most effective. Thus, use what works the best for your project, get rid of the rest, and evolve your design process as the product evolves.

2. Product design is not a linear process

A lot of product teams think design is a linear process that starts with defining the product and ends with testing. But that assumption is wrong. The phases of the process often have considerable overlap, and usually there’s a lot of back and forth. As product teams learn more about the problem being solved, the users, and the details of the project (especially the constraints), it may be necessary to revisit some of the research undertaken or try out new design ideas.

3. Product design is a never-ending process

Unlike more traditional forms of design (such as print design), the design process for digital products isn’t a one-time thing, and designers should never assume they’ll get everything perfect right from the start. Implementation often reveals gaps in the design (for example, bad assumptions about product usage, which are hard to predict without shipping the product).

To design successful products, teams need to adopt a process of continual improvement. Iterative design follows the idea that design should be done in repeated cycles. It’s a process of constantly refining and improving the product based on both qualitative and quantitative feedback data from your users. This is a great opportunity for designers to see the bigger picture, improve their work based on user feedback, and make the product inherently more valuable to users.

Circular diagram showing cycle of think, make, check
Product design is a cyclical process of data analysis, getting feedback from real users, and testing, so the product team can constantly refine its solutions.

4. Product design is based on communication

While doing great design is one thing, communicating great design is equally as important. The best concepts will fail if they don’t get approval from the team and stakeholders. That’s why the best product designers are great communicators.


The most important thing to remember when designing products is that design is for people. To design great products, you must deliver the right features, with the right user experience for the right people. Thus, define your target audience, then research their problems, and, finally, focus on building a product that solves those problems!