What are hashtags on Twitter?

[Max]

My son was just wondering why people are doing hashtags on Twitter. Like for example, #ilovepizza or #surprisinglygood? Did they just start with that, or did they do it for a long time?

[Sarosh Hadi]

Hashtags turn topics and phrases into clickable links in your posts on your personal timeline or Page. This helps people find posts about topics they’re interested in. To make a hashtag, write # (the number sign) along with a topic or phrase (written as one word) and add it to your post. For example:

I walked up so many hills today! #SanFrancisco

[Who, me?]

Hashtags have been around since before Twitter (IRC chatrooms), but Twitter is really what made them popular. They're supposed to be a way to "tag" a message with subjects or topics - so if I'm posting about a job opening, I might add "#jobs #california" at the end to help people find it, or maybe if I'm at an event, I might add "#ComicCon2013" so people see it's related. On Twitter, people can search for a hashtag, so a job-seeker may be searching for #jobs to find postings or useful information.

More and more though, people just use hashtags for the sake of using them, which is why you see ones like #ilovepizza and #OMGcantlivewithoutstarbucks