Surrender

To surrender is basically a player’s option of backing out of the initial wager. By surrendering the player only looses half of the original bet. The option of surrendering is only available to players before they make any other moves. For example, if a player decides to hit, split, or double down, surrendering is no longer an option.
Banner from Gaming Club

There are two types of surrenders, an early surrender and a late surrender. In an early surrender game of Blackjack, a player may elect to surrender before the dealer checks his down card. In a game of late surrender Blackjack the dealer will check his down card first, and if the dealer has a blackjack the player can not surrender. Many online casinos do not offer their players a surrender option.

Insurance strategy

If the dealers up card is an ace, a player will normally be offered "Insurance" to protect themselves from a dealer Blackjack. Simply meaning that if the dealers up card is an ace you are given an option to bet that the dealers down card will value 10. Insurance bets are limited to half of the players original bet wager, and are normally made by clicking the insurance button. If you do not wish to take the insurance bet, you simply click on the "Pass" button to proceed with the hand.

If the dealer does have a Blackjack, a player’s insurance bet will be paid at 2:1. Unless the player also has a Blackjack, he or she would loose the initial bet but would breakeven if he or she decided to take the maximum insurance bet. This is why the bet is refereed to as "insurance", it protects a players original bet against a dealer blackjack. Of course, if the dealer does not have blackjack, the player loses the insurance bet, and still has to play their hand.

Doubling Down

Doubling Down is a player’s option to increase their initial bet after the first two cards have been dealt. Basically meaning if a player believes he or she has a good possibility of winning the hand after the first two cards have been dealt he or she can “Double Down” and increase the bet for any amount up to the initial wager amount. After a player “Doubles Down” he or she is limited to receiving one additional card. Therefor, after “Doubling Down” a player can only hit one time.