What does it mean to “mount” slide film for processing?

Question

I just finished my first roll of a 35mm slide film and it is time to get it processed. I checked few places online and the options are to get them processed "mounted" or "unmounted".

So what do these places mean by mounting a film for processing and how does it change the quality of final output?

Answer

You can have slide film processed like normal film, left in long strips, or more commonly they are individually cut into single frames and mounted in a cardboard or plastic holder, which keeps them flat, and these mounted slides can then be put in a cartridge of a slide projector. The mounts can be seen here.

The processing is exactly the same, so no difference in quality. The mounting is done after the film is processed and dried.

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