Disclaimer
Now for the serious bit. This is all straight out of my own head, and from my own personal experience picking literally hundreds of different locks. Nothing is copied and pasted, and there's no stupid nonsense I just assumed was right and decided to write down, it's all cold hard fact. I don't have any paper credentials whatsoever, I'm not a locksmith or an engineer. But you don't need to be. Just be thankful I'm not some kid who watched a guy pick a deadbolt with a paperclip on youtube and thought it was awesome so I'd write my own tutorial.
It's taken me a couple of hours each evening for just over a week to get everything written down the way I want it, and all the pictures/diagrams are my own as well so I'd appreciate it if you didn't steal the thing and put your own name on it. I didn't bother putting little copyright things on any of the pics cos it's not copyright and that'd be stupid. I'm not gonna be an internet tough guy and make threats, just don't do it... if you wanna share, just link it and give credit where it's due. I really don't care as long as you're not making anything off it.
I've done my best here to make this worth your time instead of re-wording the basic theory and technique like every- one else seems to. As far as the principles go, I pretty much had to even at that, I've put a lot of time into explaining everything in as detailed and clear a manner as possible.
Edit from Chris:
We have kept the majority of this document intact, improved the language and expanded on a few newly available resources:
Some aspects of lockpicking are more easily learned from video guides on our website; we touch on a broad range of lock types, but understanding the theory and repeated practice are super important as with any skill you pick up.
Have fun learning about locks and lock picking. I find that personally, it relaxes me, improves my ability to visualise problems in my head, and helps to develops finger dexterity. Gifting a set of picks and lock to friends is uniquely unusual and fun. Enjoy!