Difference in GC and TRIM?

[SuperDave1685]

Call me a noob, but could someone explain the difference between TRIM and GC to me? I've heard of GC, but I'm not sure what it it. I know what TRIM does, in regards to helping read and write to half-full/deleted pages to help keep SSD performance up. But I have no clue what CG does. Anyone care to explain? Thanks!