Binding is a means of providing players with alternatives to their default starting points. You can have two bind points.
One must be at a bindstone, or an area designated as bindable. In Albion, a bindstone is a large engraved rock surrounded by four smaller stones. In Midgard, the bindstone consists of a large rock leaning against a smaller one, with a column inscribed with runes to either side. In Hibernia, the bindstone is a tall, conical stone surrounded by mushrooms. Bindstones are realm-specific. A Midgard player cannot bind at a Hibernian bindstone, etc.
Bindstones are usually located in towns, villages and castles, though some may be in other locations. If you type /bind while near one of these stones, you will receive the message "You are now bound to this location." If you type /bind it will attempt to bind you at your current location. If you cannot, you will receive a message stating that you cannot bind there. You will also receive a message stating what your previous bind point was.
Your second bind point must be in a house. This can either be a house you own, or a house where you have had permission to bind. To bind at a house, you must enter the house, locate the bindstone (which will be in the basement level), and type /bind while near it. This will not overwrite your "normal" bind.
When you die, you can type /release to return to your normal bind point, or /release house to return to your house bind point. If you are in the New Frontiers or a battleground, typing /release will return you to the nearest border keep bindstone, or the portal keep. There is a bindstone at each of the two border keeps for each realm. To release to your "normal" bind in the New Frontiers or a battleground, type /release bind.
If you have never bound in any location, typing the default bind point will be your starting location, which is generally near your base class trainer.