who uses hashtags and what is a hashtag?

[sparkle00999]

what is a hashtag anyway?

[MarkNJ]

Definition: The # symbol, called a hashtag, is used to mark keywords or topics in a Tweet. It was created organically by Twitter users as a way to categorize messages.
Using hashtags to categorize Tweets by keyword:

People use the hashtag symbol # before a relevant keyword or phrase (no spaces) in their Tweet to categorize those Tweets and help them show more easily in Twitter Search.
Clicking on a hashtagged word in any message shows you all other Tweets marked with that keyword..
Hashtags can occur anywhere in the Tweet – at the beginning, middle, or end.
Hashtagged words that become very popular are often Trending Topics.
Example: In the Tweet below, @eddie included the hashtag #FF. Users created this as shorthand for "Follow Friday," a weekly tradition where users recommend people that others should follow on Twitter. You'll see this on Fridays.

Using hashtags correctly:

If you Tweet with a hashtag on a public account, anyone who does a search for that hashtag may find your Tweet
Don't #spam #with #hashtags. Don't over-tag a single Tweet. (Best practices recommend using no more than 2 hashtags per Tweet.)
Use hashtags only on Tweets relevant to the topic.