Attributes are fields that provide relevant information about each contact. They come from the data sources, since the attributes are generated on data import.

The main function of attributes is to provide relevant information about your audience (for example, knowing how many purchases a customer has made) and create segments. You will also be able to customize your messages with this information.

In 'More - Attributes' section, you can see the available attributes for the project you are working on:

There are automatic attributes, that are generated directly for each type of integration (for example, the contact's name), and custom attributes, which you can edit or create.