I was walking through lower Manhattan on the way to work one morning a couple of years ago when I saw a guy in a hardhat peering through something like one of these things mounted on a tripod:
I'd seen this sort of equipment before, lots of times near construction sites or operated by crews on the side of the road. But I never knew exactly what it did. So I asked him: What is that thing? It was surveying equipment, the guy told me, which helps take measurements—like distance and elevation—for mapping and other planning purposes. Ohhh. Cool.
And it was cool. Not just the fact of the thing but my newfound (if limited) understanding of it. There was something so satisfying about a simple exchange that answered a question I'd wondered quietly for years. Which helps explain why a site like What Is This Thing Called is so delightful. It's a simple Tumblr, made in the spirit of a similar Reddit thread, that features photos of obscure, forgotten, or otherwise ambiguous technologies. Anybody can comment on the photos to help clarify what the thing is.
A lot of the mystery things are of commonplace items. There's the plastic pamphlet that a restaurant bill arrives in (a check presenter) and those stumpy cylindrical posts that prevent cars from driving onto pedestrian spaces (bollards). Others are things that happen, phenomena rather than physical objects themselves—like the kink in a landline cord.
It's sort of like Quora for pictures, a one-stop place to tap the knowledge of the crowd—which is really useful if you want to know what to call something (surveying equipment, for example). Put a random question before a big enough audience and you're liable to match the right human with the right object so you get the information you're looking for.