Once you and your dentist have decided that you need a crown, the process may involve several more steps if you need a root canal or are getting an implant (which is a surgical procedure and requires recovery time before a crown can be placed). For implants, you'll probably get a temporary crown, made quickly in the dentist's office out of a white composite material (usually synthetic resins) and attached with a weak cement to allow for easy removal when the real crown is placed over the implant.
If you still have your tooth, however, it has to be prepared for a crown. Usually this means grinding it down (after your dentist has taken an impression if necessary). Some of the healthy tooth will probably be ground away to allow the crown to fit properly. This is why crowning is a permanent solution -- if ultimately a crown doesn't work for you, the remaining tooth will have to be pulled and you'll need an implant or another dental appliance like a bridge. How much of the tooth is removed depends on the type of crown you get; a gold crown requires the least amount of grinding because it can be as thin as half a millimeter. Porcelain crowns can be twice as thick.
On the other hand, your tooth may be so damaged that the dentist has to strengthen it to prepare it for a crown. He may build it up with a composite material, or if you've had a root canal, perform a post and core. This means inserting metal posts into the empty root canal area and filling around it with a material like latex. Post-and-cores are different from implants because you still have the root system and some existing tooth left.
When the crown is ready, you and your dentist need to agree that it matches the color of your other teeth (unless you got a gold crown, of course) and fits properly before cementing it. A poorly fitting crown can invite bacteria to grow underneath, cause problems eating, wear down other teeth or just plain hurt. Crowns should be treated like the rest of your teeth -- avoiding acidic foods and biting on things like ice will help keep them in good shape. Most are meant to last at least a decade but usually last longer.
While the whole story of dental crowns may be fascinating, getting one isn't high on most people's wish lists. Take good care of your teeth and reading this article may be closest you come to a crown!