So recently I've been getting together with a few friends and writing some music and stuff.

Now both my friends receive lessons where as I am self taught. Yesterday I was doing some lead playing and they both commented on how my thumb on my fretting hand is wrong. I place it closed over the top of the fretboard but no enough to touch the strings, where as they both pin it to the back of the fretboard.

Now I was wondering if I've been playing in a way that makes me a lesser player? because honestly in all 7 years of playing I've never noticed but now I'm self conscious about it.
i wouldnt worry to much,you will alot of good players who have the thumb over fretboard.
A lot of blues players do this, but if you want to play faster stuff its better to do the thumb on the back of the neck thing...

And as the dude said up there, it will make using your little finger easier!
Marshall Vintage Modern 2466 and Gibson Les Paul Custom is litteraly sex in my ear!!!

"THESE AMPS GO TO 11!!!!!!!!!!"

Jimi Hendrix had his thumb way over the top of the fret board
I have my thumb like that too but recently I have been playing with my thumb alot lower on the neck, i find that my fingers are more perpendicular when i have my thumb near the middle or bottom of the neck

I dont think there is a right or wrong way
I dont really have a problem at all playing fast stuff and using my little finger. And it's not really 'closed over the top' more that you can see it poking up from the back of the neck.
don't worry too much. placing it on the back just makes it easer to use ur pinky, and spread ur fingers a bit further
The thumb should be behind the neck, it should only be over the neck when you're performing bends/vibrato. The thumb behind the neck allows you to have better stretch, facilitates finger independence and reduces tension.
Speed is a by-product of shut the fuck up.
Putting it on the center of the back of the neck allows for better economy of motion for your fingers when fretting, but curling the thumb gives you more grip.

In my experience, you'll hear more from classical players that it's 'supposed' to be at the rear center, and more from people who play chords heavily that it goes to the edge of the neck, but in all honesty, both have benefits, and there's no 'right or wrong' way unless what you're doing is hurting your body.

Play how you play, and unless it's unhealthy for your hands/arms, realize that it's all preference for how you get the job done within your style.
Do you feel warm within your cage?

And have you figured out yet -

Life goes by?
Quote by Hydra150
There's a dick on Earth, too
It's you
Yeah, I kind of agree with strat0blaster. And in fact, I think you need to learn both ways. This will give you an edge because you won't be hindered by not having one of the options at your disposal if it is in fact the better option. For some songs, I notice that you can play things both ways, but one is always clearly the better option. Like bending. That is clearly a case that calls for thumb over.
You need thumb over for bends and rock vibrato - but you need thumb behind for barre chords and to effectively use all four fingers. So, yes, you're limiting yourself as a player.