What are hashtags and how to use them in a proper manner?

Hashtag is a word or phrase preceded by a hash sign (#), used on social media sites such as Twitter, Facebook, Google+ and other social media networks to identify messages on a specific topic.

How to get more out of social media by mastering the hashtags?

Watch this video to have the answer of this question:

https://www.youtube.com/watch?v=tXCVP-2ixYA