Tags are labels that allow you to categorize your people based off attributes or keywords. You can use tags to indicate industry, conferences attended, even hobbies or interests - There is no limit to how many tags you can apply to a person.
There are multiple ways to tag a contact in your account.
Inline from a list
As a Bulk Action
From the Person's Profile
From the Add/Edit Form
Admins can add, remove, and edit Person Tags in Account Settings or add new tags from within the list view.