what does it mean when a sentence starts with # on twitter?

[site]

like this
ex: i want the new justin bieber cd #myworld2.0

[Matt]

is a "Hash Tag" (also called a pound sign when used on your phone). Hash tags are a way for Twitter users to tag different text they wish to share others that might be searching for that hash tag word combination through a Twitter conversation engine.

Twitter also uses "Hash Tags" to determine what people are talking about cross their micro blogging platform. In reality though, by know means does Twitter's "Hash Tag" method determine trending topics though as very few people use #HASHTAGS

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