The plunger is probably the most overlooked and under-appreciated tool in the home. Most people don't think about it until the need it. If you find yourself needing a plunger, don't just pick the first one you come to. Selecting a good plunger can make using it correctly that much easier.
OK - In a pinch, this plunger will do. It is the basic model. There's not much to it so there's not much to say about it.
Better - Very powerful but this model does not always conform to every application. The plastic that it is made of has a hard time making a seal, but if it does watch out.
Best - This type of force cup plunger is best for all around home use. It can conform to pretty much any toilet, lavy or kitchen sink because of the soft rubber.
For step by step instructions on using a plunger read How To Unclog a Drain.