Blind baking is what you do to an uncooked pie shell when you want a cooked pie shell. That is, you take a pie shell and throw it in the oven until it's done.

Of course, it's never that simple. The steps you need to follow are something like this:

  1. Get yourself an unbaked pie shell. You could buy a frozen one or make your own -- there are several solid looking pie crust recipes on E2 (the one by anthropod looks like the most general basic pastry, IMHO). Roll out the crust and put it into a pie plate.
  2. Prick the bottom of the shell with a fork (aka. docking the crust). If you don't do this, steam (caused by the water boiling) will be trapped in the crust. This will leave you with a too-wet crust with with big, unattractive bubbles formed by the expanding steam.
  3. Line the shell with parchment or foil and weigh down the bottom of the pie. This can be done with pie weights, dried beans or uncooked rice (or stones, or pennies, or ...). This keeps the bottom of the shell from puffing up. The shell should be nearly filled with the weights. [If you want to skip this step, go ahead, the world won't end. Just make sure the crust is thoroughly pricked and it should come out okay.]
  4. Bake in a pre-heated oven. The details of the baking are up for debate. After surveying the cookbooks I have on hand, I have temperatures from 375-450°F for 7-15 minutes. The two most trusted cookbooks I have agree on 400°F (220°C) for about 12-15 minutes (or until it's golden brown).
  5. Finish your pie.

Blind baking is done when the cooking time needed for the filling would be too short to properly bake the crust. This generally includes cream pies and lemon meringue pie, where the filling is cooked before it's put in the shell. The pie is generally baked for only a few minutes as a whole, often just to brown the meringue. Because of this, your blind baked pie shell should be lighter then you want your finished product to look. It will brown more in the final baking step.

What you don't want to do is miss the blind baking step when needed, as I found out in my first pie-making attempt. No matter how good the filling is, if you put it in a raw pie shell, it's going to suck.

Pies that bake for longer don't need to be blind baked -- you start with a raw shell. Fruit pies, for instance, bake for nearly an hour -- plenty of time to get the crust cooked.