Developing a good release is crucial to the development of a good swing.  A good release will give you great power and accuracy with less effort, and a poor one will do exactly the opposite.  If you hit a huge slice, or can't find distance even if you swing out of your socks, chances are you are not releasing the club correctly.

So what exactly is a release?  I like Jack Nicklaus's description of it.  It is returning the club to its fully extended address position.  This means that upon impact, the clubshaft and your left arm (right arm for leftys) should form a straight line.  By doing this, you have fully unloaded all the stored-up energy that you created in your wrist hinge on the backswing, and this lets you take advantage of all your potential power.

Let's backtrack and talk about that wrist hinge and the resultant "lag" in the swing, because I think many people misunderstand its use.  I'm sure you've all heard how these pros have so much lag in their downswing coming into the ball, and how much power that gives them.  And conversely, we hear about the horrors of amateur golfers "casting," that is, releasing too early in the downswing and not creating any lag.

This is true!  But what I see a lot of guys do is hold onto their wrist hinge throughout the downswing in an attempt to 1) avoid casting and 2) create lag like the pros.  Well, this is only half of the equation!  The problem here is that if you never release the club, it will never become fully extended--there will be an angle between your left arm and the clubshaft.  This, in turn, means the club has not reached its maximum potential speed.  The second, and more damaging problem:  If you don't release the club, your clubface will be wide open at impact.  I think that the majority of golfers who slice uncontrollably do it because of a failure to release the club.

Here's a great example.  Watch this video of everyone's favorite, Tiger: http://www.youtube.com/watch?v=XPJtK-DxnV4&feature=PlayList&p=E7E7E1594BF764D5&playnext=1&playnext_from=PL&index=11

Now, notice on the downswing how he does in fact retain his wrist hinge for a long time.  But look at impact:  his left arm and clubshaft form a straight line.  This is a perfect picture of a full release!  This is the kind of release we should all be looking for.  Notice how Peter Kostis only comments on the angle retention, and not about how he releases that angle fully at impact.  He says the angle is where Tiger's speed comes from, but that's only half of the story--it's the release of the angle!  This is the kind of misleading teaching that keeps us from fully releasing the club!

Here's another video of Woody Austin hitting an iron.  We are all taught to hit down on the ball with an iron, but we need to make sure that we do that while still forming a straight line with the clubshaft and left arm at impact, as Woody does here: http://www.youtube.com/watch?v=8lBWFeKZto4&feature=related

Okay, so I've made the case for making a release.  So how do you release the club after all?  Well, I'm going to return to Jack Nicklaus here.  Grab any club and swing it to the top like normal.  You should have created something close to a 90-degree angle between your left arm and the clubshaft.  Got it?  Okay, now without moving your lower body (stay on your right side, in other words), simply unhinge your wrists.  That's a release!  That's what your wrists should do as you come into the ball.  Of course, by staying on your right side like I told you to, you have made the classic "casting" motion by releasing the club without unwinding your lower body.  Now, swing to the top again, and start down with your lower body this time...but go ahead and release the club from the top like before.  But check it out:  The speed of your lower body unwinding before your upper body causes your arms and wrists to hold their angle until the last instant, even if you feel like you release from the top!  This is why Jack Nicklaus felt it was impossible to release the club too early--as long as you get to your left side.

Here's proof of this:  Watch Jack Nicklaus here. http://www.youtube.com/watch?v=4smKIu2uARU

When it goes to the split-screen slow motion, watch the large lag he creates.  But remember that he always felt that he was releasing the club from the top of the swing.  However, since he always started down with his lower body, the lag he created was huge, but since he still felt that he released from the top, the club was fully extended at impact.  This gave him maximum power and accuracy.

So for those of you who have been told to retain your wrist angle for more power but find yourself actually losing power and accuracy, remember this:  Lag is simply a product of initiating the downswing with the lower body.  It is impossible to release too soon if you do this.

And all you slicers out there:  If you try this release method and notice that you hit a huge hook all of a sudden, don't despair--it's time to check your grip!  You probably have been gripping too strongly (that is, hands turned to the right for right handed golfers) in order to fight your slice, and now that you have a proper release, your grip is causing a hook.  Weaken your grip (turn your hands to the left more) and you'll be hitting straighter than ever!

Whew!  Lots to say about this.  Let me know if you have any questions!  Hope I've helped you guys!