TITLE: group theory for non-mathematicians
QUESTION [19 upvotes]: A very smart non-mathematician friend is looking to learn about groups, and I was wondering if people might have suggestions (this is NOT a duplicate of this question, since a textbook is not what I am looking for, at least not at first).

REPLY [2 votes]: I recommend Carter's Visual Group Theory. It makes heavy use of pictures and diagrams (hence the name) and I found it very clear.