Lossy and non-lossy compression explained, with examples and an outline of how JPEG compression is performed.
MPEG-4
There is nothing so frustrating as watching a great movie but being unable to save it, or watch it on your iPad or Apple TV. It all comes down to formats.
No matter how much disk storage you have, it just seems to fill up. Compressing little-used and archived items might be a good way to save space. Does it?