Tag

A tag is like a label and has two uses:

1. For example, on the photo sharing website Flickr, if you had a photo of a red balloon you would tag it with the terms: balloon, red and round. If someone were to search for "red," your red balloon photo would appear, along with other photos in which their owners tagged the color "red."
2. Tags are also used in the coding process to label commands that computer languages understand.