Facebook has made hashtags clickable in the same way as other services like Instagram, Twitter, Tumblr, or Google+ as part of efforts to help users more easily discover what others are saying about a specific topic and participate in public conversations.
Hashtags are created by writing numeric along with a topic or phrase written as one word and adding it to your post. This simple step turns topics and phrases into clickable links in posts on your personal timeline or your Page, and helps people find posts about topics they are interested in. The new service is not yet available to all, but Facebook has said that it will roll out hashtags to more and more users in the coming weeks.
It is important to note that when making something into a hashtag by adding a in front of a word, acronym or phrase that there should be no spaces. Upper and lower case is not differentiated. On Facebook, as soon as you use the numeric symbol a blue box will appear over your tag. Then click Post. Your tag will appear in bold within your status update.
Many users already post hashtags anyway, so Facebook has taken the view that it makes sense to make them workable by making them both clickable and searchable.
Hashtags from other services, such as Twitter, are also clickable, meaning users will be able to compose posts directly from a hashtag feed and search results.