In poker, one of the motives for betting or raising is to give your hand protection, which means to encourage opponents to fold a drawing hand that might otherwise improve to beat yours. This is generally made hand that you perceive as vulnerable to an opponent's drawing hand. This differs from a bluff in that the latter can win only when the opponent folds, while a bet for protection is made with a hand that is likely to win a showdown, but is not strong enough for Slow Playing.
It is especially important to bet for protection when there are multiple opponents. For example, if your hand is presently the best, but each of four opponents has a 1-in-6 chance of beating you, the four combined are actually a favorite to defeat you, even though each one is individually an underdog. If you bet, some or all of them will fold, leaving you with fewer opponents and a better chance of winning.
The term protection is also often heard in the context of an all-in player (see poker table stakes rules), because a bet by any player serves to protect the hand of an all-in player just as it protects the bettor (and possibly more so). To deliberately make such a bet solely to protect a hand other than your own is a form of collusion.
A player may also be said to "protect" his or her cards by placing an object like a specialty chip or miniature figure upon them. This prevents the player from having his cards accidentally discarded by the dealer.
In poker, the strength of one's hand (that is, how likely it is to be the best according to the rules of the game being played) is often called its value, but discussions of poker strategy often use the term in a more specific sense to describe a type of bet: A bet "for value" is a bet made for the purpose of increasing the size of the pot, and which the player wants his opponents to call. This is in contrast to a bluff or a protection bet (though some bets may have a combination of these motives).
Most of the time, this is because the player believes his hand is valuable in the first sense, and he therefore wants his opponents to put money into the pot that he expects to win from them at showdown. In certain situations, though, even a drawing hand that is not currently the best can value bet: For example, on the next-to-last betting round of a fixed limit game, if a player surmises that he has a 1-in-4 chance of being dealt a final card that will give him a winning hand, and there are six opponents remaining, he can bet for value even though he will lose three out of four times, because the one time he does win he will win more than three times the amount bet (so the bet earns money in the long run). This is still a value bet, because it is made hoping the opponents will call and build a bigger pot in anticipation of winning (even though the win is only statistical).