The Lempel-Ziv source encoding (LZ for short) is able to asymptotically approach maximum efficiency because it adapts to the source. It does this by keeping a

The Lempel-Ziv source encoding (LZ for short) is able to asymptotically approach maximum efficiency because it adapts to the source. It does this by keeping a dictionary of past phrases, and referring back to that dictionary as it encodes new stuff. (There are several ways to do this, all offering guarantees, so there are several flavors of LZ.) The key is that the dictionary changes per-source. This adaptive encoding would not really work for direct human interpretation, because you'd have to maintain that dictionary somehow in your head, separately for each source. You'll note that our selection of acronyms and terms of art ("ROC curve", "tach", "JS") has something of this flavor, though -- and the lexicon is adaptive within each universe of discourse.