show some useful models, and, finally, we'll briefly describe what an interaction designer usually does. Interaction design is an important component within the umbrella of user experience design. Interaction design can be understood in simple, but not simplified, terms. It's the design of the interaction between users and products. Most often, when people talk about interaction design, they talk about software products like apps or websites. The goal of interaction design is to create products that enable the user to achieve their objectives in the best way possible. If this definition sounds broad, that's because the field is rather broad. The interaction between a user and a product often involves elements like aesthetics, motion, sound, space and many more. And, of course, each of these elements can involve even more specialized fields, like sound design, for the crafting of sounds used in user interactions. As you might already realize, there's a huge overlap between interaction design and UX design. After all, UX design is about shaping the experience of using a product. And the most part of that experience involves some interaction between the user and the product. But UX design is more than interaction design. It also involves figuring out which experiences will be the most relevant for your users, the best way of creating them and the best way of validating the design. For that, you also need user research, personas, user testing and so on. The 5 Dimensions of Interaction Design is a useful model to understand what interaction design involves. The first dimension is words. Words, and especially the ones we use in interactions – like the button label on the image – should be meaningful and simple to understand. They should communicate information to users, but not so much information that they overwhelm the user. The second dimension is visual representations. This concerns graphical elements like images, typography and icons that users interact with. Icons and images usually supplements the words used to communicate information to users. Even if you don't know Chinese, you can probably tell the camera app from the map on this Android interface because you recognize the icons. The third dimension relates to the physical objects that users use to interact with a product. This could be things like a laptop, a mouse, a touchpad or a smartphone. It also relates to what kind of physical space the user interacts in. For instance, is the user standing in a crowded train while using the app on a smartphone? Or sitting at a desk in the office, surfing the website? These factors all affect the interaction between the user and the product. The fourth dimension is time. While this dimension might sound a little abstract, it refers to aspects of the interaction that unfold over time, such as animation, videos and sounds. Motion and sounds play a crucial role in giving visual and audio feedback to users' interactions. For instance, look at the feedback an iPhone gives you when you send a message. The small animation and the swoosh sounds give you subtle feedback that your message has been sent. You can also think of time in relation to the amount of time a user spends interacting with the product. Can users track their progress or resume their interactions sometime later? – and so on. The fifth dimension is behavior, which basically relates to the user side of the interaction, both in terms of how they interact with the product and how they react to the product. In relation to interaction, the previous dimensions come together to define how users perform actions and operate the product. The user's reaction obviously also relates to whether you've designed the previous four dimensions to create a compelling and positive experience for the user. So, how do interaction designers work with the five dimensions to create meaningful interactions? To get an understanding of that, we can look at Usability.gov's important questions interaction designers ask when designing for users. The first is "What can a user do with their mouse, finger or stylus to directly interact with the interface?" This helps us define the possible user interactions with the product. The answer to this question obviously depends on the type of product. So, you have to look at the action possibilities of the particular product you're working with. For instance, an iPad has a number of predefined gestures available to the user and designer to take advantage of. The second question is "What about the appearance, such as color, shape and size, give the user a clue about how it functions?" This helps us give users clues about what behaviors are possible. If you look at the cutout from Interaction-design.org, you can see that we use the color blue to tell our users where text is interactive. We also use shading and a square shape to indicate to users that there's a button that can be pressed. The third question is if your error messages provide a way for the user to correct the problem or explain why the error occurred. This lets the user anticipate and mitigate errors. If you create error messages that make no sense to the user, they'll quickly become frustrated with your product. The fourth question asks what feedback a user gets once an action is performed. Asking this allows us to ensure that the system provides feedback in a reasonable time after user actions. In the example here, Twitter provides feedback to the user both when they input information right – with the little checkmark – and when the input information wrong – by providing information about what the problem is. The fifth question is "Are the interface elements a reasonable size to interact with?" Questions like this help us think strategically about each element used in the product. Users interact with devices of many different sizes. And what you can interact with on a laptop is not necessarily the same as what you can interact with on a phone. The final question asks if familiar or standard formats are used. Standard elements and formats are used to simplify and enhance the learnability of a product. Play control icons like the play and pause on the Apple TV remote are a good example of a widely known standard. So, what do interaction designers do? Well, it depends! For instance, if the company is large enough and has enough resources, it might have separate jobs for UX designers and interaction designers. In a large design team, there might be a UX researcher, an information architect, an interaction designer and a visual designer, for instance. But, for smaller companies and teams, most of the UX design job might be done by 1–2 people who might or might not have the title of "Interaction Designer". In any case, we can divide a lot of the tasks interaction designers handle in their daily work into two categories: Design Strategy and Wireframes and Prototyping. When interaction designers work with design strategy, they are concerned with what the goals of the user are and, in turn, what interactions are necessary to achieve these goals. Depending on the company, interaction designers might have to conduct user research to find out what the goals of the users are before creating a strategy that translates into interactions. How interaction designers work with wireframes and prototypes again depends on the job description of the company. But most interaction designers are asked to create wireframes that layout the interactions in the product. Sometimes, interaction designers might also create interactive prototypes and high-fidelity prototypes that look exactly like the actual app or website. Here, we've provided you with an overview of what interaction design is. But if you're interested in finding out more about interaction design, we encourage you to read our encyclopedia chapter called "Interaction Design – brief intro" by Jonas Lowgren. The chapter provides a great introduction to the field as well as other references where you can learn more.