As you’ll read below, there are different types of Avatars, I will focus on the Customer Persona.
The Avatar that you use will depend on what you are doing. For example, a UX or web designer would use a UX/Web Avatar. A UX/Web Avatar helps designers understand what the different users of their website are going to be doing at various stages of the user journey. This helps them design a website that is user-friendly, intuitive and that will convert more visitors to customers (or whatever the ultimate goal of the site/application is).
Small Business Owners use Customer Avatars so that they communicate and nurture their