Jonno said:
I was inspired to start this thread by a little exchange on current video formats/codecs - AVI, MP4, MKV et al...
AVI, MP4 and MKV are neither formats nor codecs; they are all containers.
MPEG-4 Part 2 and MPEG-4 Part 10 (aka H.264) are formats.
A codec (encoder/decoder) is a software library such as Xvid or x264 (actually I think x264 is an encoder only, but you get the idea).