What is a hashtag?
A hashtag is a word or phrase preceded by the # symbol. It is used on Twitter.
The question came up at breakfast the other day and I could not find a very good explanation on internet.
Really, though, it is quite simple.
A hashtag is a means of searching Twitter.
To search Twitter, you simply put that hashtag symbol # ahead of your search criteria, as #smartphones.
To Tweet something so that it can be found, place the hashtag after your Twitter. Such as #smartphones if you are twittering about smartphones.
The benefit of searching Twitter is that you are searching right up to the minute info.