Tilt is one of the more interesting concepts in poker, not because of what it is, but rather because of what it can do. When you consider all of the different fortunes that have been won and lost because of one bad mistake or one great play in one hand and you consider the way in which tilt can destroy a person's mind, albeit for a temporary period of time, it is quite easy to see how people that go on tilt can end up doing much more damage to themselves than whatever it was that put them on tilt in the first place. This is why it is important to know what tilt is, what causes it and most importantly how to fight it.
Tilt is any number of things, but for the most part it is when someone loses control of their emotions at the poker table. Usually, this has to do with a negative emotion such as anger that leads from frustration, but it can also be elation. Anything that occurs that results in your emotions taking over and making decisions for you where your logic would usually intervene counts as being tilt and that goes for any emotion whatsoever. You will sometimes also hear players refer to someone as 'steaming', but be aware that to be steaming is the same thing as being on tilt.
The most frequent cause of tilt, to put it bluntly, is a bad beat. If you happen to be in very good shape and play a hand great only to lose it in the end because of bad luck, you can end up feeling extremely frustrated. If you are not able to let go of the thought of the bad beat and it sits in your mind and festers to the point of controlling your actions, then you are officially on tilt. However, the reverse side of the coin is possible as well. You could have played a hand poorly, ended up being lucky and felt so elated that you ended up playing poorly from that point on because of the fact that you were so relieved at having won the previous hand that you stopped concentrating. Anything that can happen in a hand to affect your emotions can potentially put you on tilt and since tilt can come and go like the wind, understanding the wide range of things that cause it is critical to controlling it.
Handling tilt is by no means an easy thing to do. The best players in the world, professionals that have seen and done everything imaginable in poker, are not able to control tilt. When you watch players like Phil Hellmuth or Mike Matusow on television, you can see what tilt can do to destroy the mind of a tactical genius and of course this is why players like Tony G live to put other people on tilt; because it destroys their ability to play a good game of poker. Eventually, with practice, you will learn to control tilt better and better; this is not something that can be taught in an article but rather must be learned through experience. The best thing you can do now to control tilt is to make use