Blu-ray Disc. This has to be the worst tech acronym since FLOPS. I mean, shouldn't there be an in there somewhere? Fortunately, they're often called Blu-ray drives and discs. They usually hold 25GB. The drives are CD and DVD compatible.

The acronym the hyphen tells you what you can do with that type of disc or that type of drive.

Read-Only Memory. You cannot write to a -ROM disc, which left the factory with data already on it. A -ROM drive can read discs but not write to them, and has no use at all for a blank disc.

Recordable. You can write to one of these discs once (provided you have an -R drive). But when you're done, it's effectively a -ROM disc.

Rewritable. Another stupid acronym, that always suggested "read and write" to me. You can write to these discs, erase them, and write to them again.