LP - Long Play, a normal album.
EP - Extended Play, a short album that usually has about 3 - 6 songs.
SP - Single Play, a CD, tape, record, etc. that has only one song, (a single) on it. In some rare cases, it can have 2 or even 3 songs on an SP.
I got that CD, (insert title) by (insert band name) yesterday. It's just an SP.