Ligatures
In writing and typography, a ligature occurs where two or more graphemes or letters are joined to form a single glyph. -- Wikipedia
I don't like ligatures. Especially, I do no understand why would anyone use ligatures while writing the code. The source code is meant to be well written and working, not good-looking.
The printed book can have ligatures, I don't mind. But writing something in a text editor with ligatures on, makes no sense to me.