A tag is a keyword or phrase used to group a collection of content or to assign a piece of content to a specific person or entity.

Tagging, then, means assigning a keyword or phrase that describes the theme of a group of articles, photos, videos, or other types of media files as a way to organize them and easily access them later. A tag can also be used to assign a piece of content to another user.

For example, if you have published a few articles on a dog training blog, but not all of your blog posts are about dog training, you can assign those few posts to the tag "dog training" for easy organization. You can also assign multiple tags to a post, such as using a "beginner dog training" tag to distinguish from more advanced types of dog training posts.

If you've uploaded a bunch of photos to Facebook from a wedding you attended, you can tag your friends' profiles to the specific photos they're in. Tagging on social media is a great way to get conversations going.