Tags are a piece of meta data attached to content that helps in classification. Most content management systems allow content producers to “tag” articles to assist in sharing and finding related content.
For example, in WordPress you can add any number of tags to a blog post. A blog titled “How To Create a List in Twitter” could have the following tags: twitter, social media. As a result, the content producer can easily filter all blog posts based on those tags or the end user can search for articles or click on links to articles based on the tag.
Use in Social Media
On some social media channels tags are expressed as hashtags for the same purpose. However, social media users often use hashtags for expressive purposes.