I count 3 ways to compress data:

1. Use short strings/symbols often, long strings rarely (e.g. Huffman coding, Zipf’s law’s effect on words, I me you the / prestidigitation onomatopoeia)
2. Refer back to things (e.g. zip, gif, lz, “One if by land, two if by sea.”, symbols)
3. Remove unwanted stuff (e.g. jpg, mpg, stop reading boring stuff)

Are there any others?