What IS a "turtleback" binding?

I ordered a book with that binding  from here once and don't know how to explain it but this is what I found on the net and it's what I got.

I believe that this is when you take a paperback and affix some form of cardboard stock to the endpapers to make it more durable, like a sort of semi-hardbound edition. I've also seen this done a bit more elaborately, where the covers have been removed and pasted, sometimes under laminate, to a much sturdier binding. These are often found in libraries, especially in school libraries on popular fiction most commonly (and cheaply) found in softcover editions. Hence 'turtleback', because a shell has been placed over the otherwise soft & relatively squishy innards of a paperback.

hmm... see, that is not what I was thinking.

What I was thinking was kind of like a spiral binding with a hard (shell) cover.

Thanks, Cozi

Wow, I was just wondering this yesterday, when I saw one on Amazon described that way.  Didn't think to ask here...y'all are so darn helpful!

Cozette is correct.  They are also called "rebound" because they have been "bound again." Most commonly done to MMPB that see heavy use in libraries.  Usually it's done to books that were never issued in a hardcover version.

Remember the books that all libraries had that were solid colored covers with only the name printed on the spine? Many of those were re-bound editions designed to have a longer life in a library than a regular hardcover or paperback.  When they discovered that children were a lot more likely to choose a book with a colorful cover, they changed the re-binding method to include the original cover.  Sometimes they look like they are photocopied onto a hardcover, sometimes they look like they are encased as a layer in a laminate.

I received a turtleback edition of a foreign language dictionary that had plastic type cover instead of paper cover...