Customer Profiles are at the heart of the People Tool. A profile is created when someone signs up for your mobile application or website (and you choose to send their signup information to Mixpanel). People profiles contain any information that you collect about an individual customer, based on the information they provide and their engagement with your product. The properties sent to People (and subsequently, to the profile) are fully customizable, and will reflect whatever information you choose to send--whether that's age, gender, lifetime revenue or even something super-specific to your registration process, like favorite music genre or relationship status. People profiles also contain a customer's Activity Feed, which is a record of the different actions the customer has taken in your app or on your site.
Every Mixpanel account comes with 1,000 free People profiles (also known as "1,000 People"). You will not be billed per profile or per property sent to People. Pricing for our People plans can be found here.