The (#) is now MORE commonly known as a hashtag rather than the pound sign.
But what exactly is a “hashtag?”
According to Twitter, the # symbol (aka the hashtag) is used to mark keywords or topics in a “tweet.”
It was created organically by Twitter users as a way to categorize messages, but is now used on MOST social platforms like Instagram and Facebook for the same reason.
Hashtags are searchable on any platform--which means if you “hashtag” for example, sushi, then everyone who has ever posted about OR is interested in #sushi is now connected with your post. You can find other people’s #sushi lunches, experiences, and photos and then interact with them.
A word of caution: Don’t overuse the hashtag. #its #not #pretty #and #no #one #likes #an #over #hashtagger. (And pretty much no one is searching the word "no") Two or three hashtags in one post is enough.