According to the Laws of Cricket, an appeal is a verbal query, usually in the form of, "How's that?" to an umpire. Since the taking of a wicket is an important event in the game, members of the fielding team often shout this phrase with great enthusiasm, and it has transmuted into the slightly abbreviated form, "Howzat?", often with a greatly extended final syllable. Most players also raise their arms or point at the umpire as part of the appeal. Some players have established their own trademark appeals as well. Players from Australia, in fact, do not even say the full "Howzat!" phrase, instead just simply shouting the first part of the word very loudly at the umpire.
Although technically an appeal is required for the umpire to make a decision, in practice it is often obvious to all that a batsman is out, and the batsman may walk off the field without waiting for the decision of the umpire. This is invariably the case when a batsman is out bowled or to an obvious catch. However, the batsman is always entitled to stand his ground and wait for a decision from the umpire. In cases where he considers he might not be out, such as a catch taken low near the grass or where it is not clear if the ball hit the bat, batsmen will not take the walking option. It is then up to the fielding team to appeal for a decision. Sometimes a batsman will walk even when it is not clear to others that he is out, if in his own mind he is certain he was out; this is considered to be the epitome of sportsmanlike behaviour.
Some decisions, such as leg before wicket, always require an appeal and the umpire's decision, as no batsman will pre-empt the umpire on what requires fine judgment of several factors. Run-outs and stumpings are usually appealed and decided by an umpire, unless the batsman is clearly out of his ground and obviously out. Appealing differs vastly from sledging in the context that appealing is not supposed to be offensive or directly taunting to the other team, and more of a celebration to the appealing team. However, excessive appealing is against ICC's Code of Conduct:
Under the ICC Cricket Code of Conduct, it is considered unsportsmanlike to:
Any instances of such behaviour are punishable by fines or match bans, as adjudicated and imposed by the match referee. Australian Bowler Brett Lee was fined 25% of his match fee for excessive appealing during match two of the 2006-07 Ashes series at the Adelaide Oval when he believed English batsman Kevin Pietersen was out caught behind.