ProfilePage markup is designed for any site where creators (either people or organizations) share first-hand perspectives

It helps Google Search highlight information about the creator, such as their name or social handle, profile photo, follower count, or the popularity of their content. Google Search also makes use of this markup when disambiguating the creator, and in features such as Perspectives and Discussions and Forums.

Other structured data features can use ProfilePage markup too. For example, Article and Recipe structured data have authors, and there are often several authors present in discussion forum and Q&A page structured data.