A sneaker is more or less a basketball shoe and adjacent styles of athletic footwear.

Sneaker collecting started to become a thing in the 70s in the Hip Hop scene in NYC. Sneakers gave people the ability to easily customize their shoes to match a personal style, painting them, dying them etc. In the 80s you got the Nike's Air Jordans, which blew up the scene. You'd have a lot of shoe companies working with different celebs to drive the popularity of the Sneaker. It rapidly takes on the properties of a status symbol.

Now you have Sneakerheads, which is basically a consumer identity that is willing to spend a lot of time and money to ensure that they have a large collection of sneakers that many don't even wear. As with many things, I think there is something cool in there that was ruined by hyper consumptive capitalism.