Definition of camping...
Well, your plain vanilla "camping" is basically just sitting in a single position for an extended period of time. Usually this position will give you a strategic advantage over the other players, but doesn't have to. For instance, I've seen people "camp" by lying down in bushes and just waiting until the action passes them by, then sneaking out to deal damage.
Usually a "camping" position is one that a person will return to time and again, even if they believe their location has been compromised. They will generally fight to keep that position, believing that its strategic importance outweighs every other tactic in that particular match/game. This will involve using explosive devices (proximity mines, bouncing betties, claymores, and so forth), heavy close- to mid-range weaponry (shotguns are prime for this), or diversionary tactics (decoys are a good example of this, luring people back to this position).
By this definition, the tactics that snipers utilize fall under "camping". And yet, people give snipers an exception to their rage over "camping". Why is that? Because snipers have to utilize an increased amount of skill to kill their targets, having to aim very carefully and usually only getting a single shot to deliver death. If they miss, they have compromised their location and are now susceptible to being attacked.
True "campers" do not have to work with the limitations that snipers do; yes, they utilize the same tactics, but their choice of weaponry allows "campers" to protect themselves more effectively. Automatic weaponry or high-damage weaponry can deal with close-range enemies much more quickly than single-shot scoped weaponry, as it is easier to correct your aim at that shorter distance. This in turn allows you to more quickly deal with approaching enemies.
Regardless of all of this, however, "campers" are very easy to handle. Once you have acquired their location, you have one of two options: you can avoid the area altogether, thus not feeding their increasing score; or you can retaliate. The retaliatory option is often much more simply accomplished than one might believe; it is easy to get frustrated with "campers", but if you keep your head about you, they are easy to deal with. You can use diversionary tactics of your own to draw them out, or your own explosive devices to harm them from afar. In Black Ops, you can make use of the RC-XD to flush them out of their position or simply kill them outright. Or, if you can work with a partner, you can ambush the "camper" from two different directions simultaneously, easily dispatching him. Remember: the team that kills together teabags campers together!
Of course, beyond your plain "camping" you have "spawn camping", which is where a person "camps" in a position that gives you a good view of the opposing teams' spawn point, giving the enemy no chance to react before they are cut down, only to respawn moments later and have the same fate befall them.
This tactic is only utlized by the largest of douchebags and should be punished with a red-hot poker being forced up [THIS SENTENCE CENSORED AND REDACTED TO SAVE THE CHILDREN'S EYES AND SENSIBILITIES].
So yeah. Camping in a nutshell.
