Hashtag: It’s a word with the pound sign in front of it.
This makes any term (without spaces or punctuation) searchable on Twitter, Instagram, and Google Plus.
On Twitter you can use numbers in a hashtag like #Year2012 but the hashtag can’t only be a number like #2012.
It is not relevant on Facebook (as of 6/12/13 Hashtags on Facebook are clickable). They’re generally only seen there from cross/auto-posts. However, since they bought Instagram, there is an infusion of hashtags and I read rumors they’ll be usable in the future.
Why would you use a hashtag?
It helps give you exposure on Twitter by making terms searchable outside of your following.
- It can be used to brand your tweets (#GuruTweet, #EdmundSays).
- It can be used as a category like #music, #construction, #TwitterTip, etc. so you can find people tweeting about the same topics as you.
- It can be used for a regular online chat (like #SMManners or #KidneyChat ) that usually are scheduled and last around an hour. (By the way I like TweetChat for chats which automatically puts the hashtag in after your tweet making online chats easy.)
- It can be used on theme days like Facebook Liking Tuesday (#FBLT) or #TileTuesday.
- It can be used to denote sarcasm (#fail, #really).
- It can be used for a series of tweets that is like a word game or joke like #MisheardLyrics or #yourclosetistoobig.
- Hashtags are great for events and should be used in live tweeting from events.