A user account is for a public user who has a member status within your site.
For example, if you have a member’s section on your site, a person needs a user account to access it. A user account does not have access to either the inline edit or administration interface within Matrix.
Only backend users, system administrators, or the root user can create a user account. The account should be in a user group under the Users folder. To view an asset, you need to grant a user read permission to the asset. You can create as many user accounts as you want within your system.
You can also create an Account manager page to allow a public user to create their user account and maintain their account details.
Read User account type quick reference to understand the different abilities each user account type has in a Matrix system.