Tag: On websites, tags are used to sort or track content for users find it again -- a practice called "tagging." Tags can also be similar to browser bookmarks and are considered a form of the site's metadata (literally "data about data"). This method was first developed as a way to classify keywords on websites to help users in their searches.

There are a variety of tagging websites around the web that allow users to submit bookmarks for their favorite pages. Del.icio.us is the most popular of these types of sites, and it features a social element as well because the links are easy to share. Google also allows users to share feeds and tag pages within search results.

Another form of tagging, popular on social media websites, is the hashtag, which lets users see popular (or "trending") news topics. These tags are marked with the hash symbol or "#." Many companies also use hashtags to promote their brand and products, and TV shows will often display a hashtag during a program. These fan Tweets with hashtags can even contribute to Nielsen ratings.

Tags on social websites can also be used to denote events and online identities (e.g. tagging a person or thing in a photo).

Tags are also used on individual websites in order to organize content. A blog might use tags as a way to let users find entries about a specific topic. Users reading a sports blog, for example, might search the tag for their favorite football team to find relevant news and information on that site.

This type of tagging is not to be confused with markup or HTML element tags, which code content on a website.