Tempo
Tempo is a term that originated from Italy. It means time. Tempo in chess can be won or lost. If a player is forced to make a retreat of his piece than that means that he lost a tempo. Basically, if he moves a piece to a square and then he moves it back is like he never performed that particular move (so, he lost a move, a tempo; is like his opponent made two moves while he had made only one)

About Check and Checkmate
The main goal of chess is to checkmate your opponent's King. The King is not actually captured and removed from the board like other pieces. But if the King is attacked ("checked") and threatened with capture, it must get out of check immediately. If there is no way to get out of check, the position is a "checkmate," and the side that is checkmated loses. You may not move into check. For example, moving into a direct line with your opponent's Rook, when if there are no other pieces between the Rook and your King, is not a legal move. Otherwise, the Rook could "capture" the King, which is not allowed. If you are in check, there are three ways of getting out: Capturing the attacking piece; Placing one of your own pieces between the attacker and your King (unless the attacker is a Knight); Moving the King away from the attack. If a checked player can do none of these, he is checkmated and loses the game. If a King is not in check, but that player can make no legal move, the position is called a stalemate and the game is scored as a draw, or tie.

The Queen (110 mm.)
The queen is considered the most powerful piece on the table due to its great mobility and also because she can control and attack pieces and squares found on its range of action. She can move along ranks, files and diagonals any number of squares without being able to jump over pieces. If she finds an enemy piece in its path she can capture that piece by taking its place.

The King (115 mm.)
The king can move one square, in any direction, as long as that square is not occupied by one of its own pieces or it's not in the range of action of an enemy piece. The king can capture a piece that is on a square that it can move on. Because the way the king moves - one square in any direction, the two kings must always be separated by a square - so they don't enter one in each others range of action.

Some other chess rules
There are also some conduct rules you should know about: Don't pressure your opponent in moving too fast. Remember: this is a game of patience!
If you moved a piece you can't take back your move.
If you touched a piece than you must move that piece.
If you want to arrange a piece that might be a little bit outside a square than you must announce your opponent.
If you moved a piece on a square and you didn't take your hand off it, you can move it on another square.
If your opponent lets you, you can take back your move or move a piece different that the one you touched.
This are all the chess rules you need to know for now. There are other rules concerning how the game is played in official competitions that you can find on the world chess federation site.

How to advance in chess
Because the number of pieces reduces during the game, the objectives of the game also changes.
In the opening each player concentrates on developing his position as faster and as harmoniously as possible while trying to stop his opponent developing his position.
In the middle game much of the action revolves around trying to control the center of the chess board, trying to exploit any weakness in the opponent's position and of course around protecting your own position.
The end game is characterized by a small number of pieces on the board. Because of the small number of pieces the result of the end game is sometimes more predictable than that of the middle game. In this part of the game sometimes even the smallest advantage could be exploited into helping you win the game.
In order to play chess at a more advanced level you will have to learn a little bit about the theory of the game. This way you will learn how to identify the main objectives of the game, you will be able to correctly evaluate the position of the pieces and their values. By understanding this you will know how and where to attack your opponent or how to defend your own positions.
A very important thing you need to know when playing a game is how to evaluate the distribution of forces on the chess board. That means that you have to understand who has a better situation : you or your opponent, so you can then know what to do next.
You aleady know that some pieces are more valuable than others and that their values depends on the number of pieces on the board and on their position. Because of this, their values will vary along the three parts of the game. There are a few criteria which you have to take under consideration when estimating the status of the game. Some of the most important are: taking in account the pieces on the board (their number, strength and so on) The assessment on the mobility of each individual piece The safety of the king you can determine the mobility of the pieces on the board by looking at their freedom of movement and at the pawn's structure.

The opening in chess
The opening is the first phase of the game and in which both players develop their pieces and engage them in battle. A harmonious developing of the pieces in this phase of the game will lead to a good game for you further on.
This is why you should be familiar with the basic concepts that rule the game and the ideas behind the openings. Even from the 15th century a series of openings have been studied like : The Spanish game, The bishop's Opening, The French Defense, mostly opened and semiopened games.
With time closed and semiclosed openings started to by analyzed. This kind of openings lead to a positional game and at least some notions of strategy were required in order to play the game. This days there are many books and publications written solely on this subject.
If you are a beginner it's a good idea to start out with learning just a few openings. It's also a good idea if those openings lead to opened and semiopened games; while playing this kind of games you will be able to develop your tactical sense. You should start studying closed and semiclosed games after you have learned a few notions of strategy. A set of rules you should follow The main idea behind all openings is to develop your pieces as harmonious and as fastest as possible and in the same time to disturb your opponent's positional development. There are a few general rules you should follow when developing your pieces: make one of your first priorities the control of the center of the board using the pawns and your other pieces.
When moving the pawns you should have in mind a good structure for them. This is very important as the pawns dictate where your strongest squares are (Remember : the squares that are under the control of the pawns are your strongest ones).
Don't move the same piece more than once in the opening unless it's necessary. This way you won't lose any precious tempo and you will focus on developing your pieces.
Don't get the queen too fast in the game. Activate the knights first and then the bishops. Choose the best square for a piece and move it directly there. Don't waste your time by doing some intermediate moves.
Castle as soon as possible Don't move too many pawns in the opening. While deciding your move choose the one that is more active, that threatens something or that puts the opponent in difficulty. Don't sacrifice a piece without a clear motivation.

The middle game in chess
The study of the middle game is different from that of the opening. In the opening it's useful if you study and understand all the theoretical possibilities.
In the middle game, however, you cannot study all the theoretical possibilities due to the great complexity of the game at this point. That is why in this part of the game you have to know how to evaluate the position. If you read piece hierarchy you already know how to evaluate the strength of your pieces. Your situation in the game is not only given by the number of your pieces and their strength but also by their mobility and their position on the chess board. Once you estimated your situation you can start developing a plan. But what kind of a plan should you do? What exactly is this plan? Your plan will be composed of a succession of strategically operations. It could be large and very complex or it could be smaller and simpler. When making the plan you can decide wether you should attack or defend.
You can also decide wether you will exchange pieces so you can get to the end game faster. Your plan will almost allays contain other smaller plans. They might have as their objective capturing an enemy piece, isolating an enemy piece, controlling some strategic square or some other immediate action.
When you make the plan you have to take in consideration the main element that characterize the current position. For example: if you have an extra piece than your plan will have to focus on taking full advantage on that extra piece; if you have some positional superiority you must use it in your advantage. On the other hand if you have a weakness your plan has to focus on strengthening your game and eliminate that particular weakens.
You should always remember an important rule : if you discover that you have some sort of superiority in the game than you have to take full advantage of it immediately and not wait. If you wait and don't attack, your opponent might find some extra resources and reinforce his position. On the other hand if you have a weakness you have to play in such a manner that you will eliminate that weakness.
A good way you can protect yourself against enemy attack is by exchanging the pieces (this is usually a good thing to do only when your enemy has a positional superiority; if he has an extra piece then by exchanging the pieces you will usually make him a favor and take the game faster to the endgame where that extra piece will make a huge difference).
In order to make your plan you have to be familiar with tactic and strategy.
When we talk about strategy we talk about establishing the purpose, about developing the long term plan. Strategy is a more abstract notion than tactic.
Tactic involves the short term plan; it's a solid notion that usually has as its final purpose gaining an immediate advantage. Many new players spend a lot of time learning a lot of strategy notions and openings.
First start learning tactic. This way you will escape from the rigid rules of strategy and learn to think independent of those rules.
Strategy is not a bad thing but because it is an abstract notion it's just a good idea if you start studying it more seriously later on, after you get more comfortable with chess.
Remember : in order to have great games you have to combine tactic and strategy; this way you'll know how to make your long term plan and how to immediately take advantage of your current position.
Tactic in chess usually involves a succession of moves which are based on forcing the opponent into making moves that disadvantage him.
The purpose behind the tactical procedure is to gain material or positional advantage or to save the game. This combination of moves is usually spectacular because at a less careful analysis of the board it is hard to spot the objectives behind it. In order to control the middle game you have to be familiar with elements of tactic and strategy. Strategy involves establishing the purpose of the game and making the general plan by analyzing the position and is a more abstract notion than tactic.
Tactic and strategy must be combined together in order to help the player to determine what must be done and how that will be done. There is a common misconception that you can only learn strategy and that tactic is a matter of talent. That is not true. You can learn tactic just like you would learn strategy. All the way from the beginning of the history of modern chess there have been noticed recurring positions that kept appearing in the game. This positions lead to the theory of the end game and that of tactic.
It's easy to imagine such typical positions in the end game (where because of the limited number of pieces on the board the same ending can occur again and again). Well, pretty much the same thing is happening in the central game too (although there are a great number of pieces on the chess board, in this part of the game, only a few actively participate at the tactical operation; the great number of pieces on the board also implies that the typical positions in the central game have a more general aspect then the position from the ending).
You may have heard about the notion of combination.
A combination is a particular case of a tactical maneuver in which a sacrifice is being done. One of the great chess players of the world, Botvinnik, gave a good definition of this notion: " The combination is a forced version of sacrifice". Botvinnik states that the forced tactical maneuver, without a sacrifice, must not be mistaken with the combination.
So, in the end, you could say that the thing that characterizes the combination is the sacrifice.
When you want to apply a tactical maneuver, you have to focus on two elements: on determining wether you should start the maneuver. You have to take this decision based on the position on the board (an exposed king, a piece which has no protection and so on). Remember: you should start a procedure that involves a sacrifice of some sort only when your opponent has a weakness and only when you know that this procedure will bring you and advantage. On actually applying the tactical maneuver.

The endgame in chess
The end game is the last phase of a chess game. This part of the game is characterized by a relatively small number of pieces on the chess board. The end game is the most analyzed part of the game. There is a huge volume of information about it, many chess books focusing specifically on this part of the game. The reason for this is that in end games certain patterns in positions appear to repeat themselves during games. That means that, because there are relatively few pieces on the board, a particular position may appear more than once in your games. Many beginners make the mistake of overlooking this part of the game as they believe it to lack any spontaneities. They believe that this phase of the game is only about calculating the possible moves. That is not true.
Although it involves the cold, mathematical like, analysis of the game, the end game can also contain amazing tactical procedures and combinations.
Just look at the grandmasters : they all exceed at this part of the game.
Another argument in favor of studying more careful the end game is that in this part of the game, supposing you know how to play it, you could take benefit of even the smallest advantage you gained during the opening and middle game. Of course, if you have a disadvantage you can sometimes end the game as a draw. For example if you reach to a point where on the chess board there are only your two bishops your king and your opponent's king do you think you can checkmate his king? If you are familiar with this kind of an end game you probably will. But if you aren't I'm almost sure that you won't be able to checkmate.