knowing all the parts of a guitar like the tray & string numbers.
definitely, taught myself and i think im a pretty good guitarist considering im only 14 =], but if you want to learn cooler stuff like improvising, song-writing, you will need to know theory, which is easier with a teacher, but starting out, yes, you can learn by yourself, start with chords, then go to power-chords and tabs, that’s what i did, and in my opinion, the chords really helped set up a good foundation for me, go to 911tabs.com, a who bunch of songs there, good luck! guitar is such an amazing instrument, i have never regret learning it, actually can’t ever imagine myself if i havn’t learned it