Like can be used as multiple parts of speech (comparing similar things, in similes, a synonym for “enjoy”), but it’s slang usage — introduced into youth culture by “valley girls” in the 1980s — is hard to pin down.

• “Oh my god, it was like the worst date I’ve ever been on. Richard was like such a jerk!”

In this example, like could be mistaken for a preposition meaning “similar to,” but it’s actually not! When dropped into sentences in this manner, like is a discourse particle or discourse marker which denotes topic changes, reformulations, discourse planning, stressing, hedging, or back-channeling.

In practical terms, “like” is the word that just falls into the gaps in speech when you might otherwise say “um” or “uhhh.” If you want to hear like in action, there is no better example than Shoshanna from the TV show Girls. She’s like the best!

Important note: Peppering too many likes into conversation can make one sound childish and frivolous — fine for parties but probably not job interviews (but most Americans under the age of 35 say the word more often than they probably realize).