What do libraries do with old magazines?

I'm curious to know, what exactly do libraries do with those outdated magazines that have been gathering dust on their shelves for years? Do they simply discard them to make room for newer publications? Or do they have some sort of system in place to recycle or repurpose them in some way? It would be interesting to understand the process and the reasoning behind it, as it could potentially offer insight into the library's approach to managing its resources and preserving knowledge.