What is the meaning of Hashtag?

A metadata tag, signaled by a preceding hash sign (#), used to label content.

The hash sign itself, especially when used as part of a hashtag.

To label (a message) with a hashtag.

hashtag

hashtag (metadata tag)

hashtag (symbol)

hashtag

alternative spelling of hasztag

hashtag (a tag with a hash sign)

hashtag

Source: wiktionary.org