user13189: I believe the question How to start learning chess? is actually two questions only one of which is a duplicate. This question is a fixed up version of it which asks only the other one of those questions.
Would it be possible to explain the rules of chess in a nutshell? A clear short description of the rules is nowhere to be found but I'm sure it can be explained very simply.

user12873: How to win: preventing the opponent's king from moving while attacking it. This is a checkmate.
That's the goal of the game. The rest of the rules just relate to how each piece moves.
King: Can move one square in any direction.
Queen: Can move any number of squares in any direction, but can't jump over pieces in the way.
Bishop: Can move any number of squares along any diagonal it's on, but can't jump over pieces in the way.
Rook: Can move any number of squares horizontally or vertically, but can't jump over pieces in the way.
Knight: Can move in an L-shape. 2 squares horizontally and one square vertically, or 2 squares vertically and one square horizontally. It can jump over any pieces in the way.
Pawn: Can move one square forward, and has the additional option of moving 2 squares forward if it's on its starting square. However, it captures enemy pieces by moving one square diagonally in either direction. The pawn is unique in that it captures and moves differently (unlike all other pieces). In addition, if the pawn reaches the end of the board it turns into a queen, rook, bishop, or knight (your choice).
Also, the game could end where no one wins, a tie or draw. This can happen in a variety of ways:

Both sides only have a king left.
Neither side has any material left that's sufficient to possibly make a checkmate. Any example is one side having a king and knight vs a lone enemy king.
A position has been repeated three times. This is called a three-fold repetition.
One player offers a draw and the opponent accepts.
Stalemate: one side has no moves left because his king is trapped and the rest of his pieces have either been captured off the board or cannot move. This is very similar to a checkmate, except that the trapped king is not being attacked.

I've left out some rules, but this is the meat of it.

user4418: The definitive guide to chess is given in the FIDE Laws of Chess. The game itself is defined by the first five articles and this is short. 
There are many more articles, appendices and even guidelines in the FIDE Laws of Chess which cover over-the-board competition rules and practices but these are not required for a basic understanding of the game, only for tournaments.

13189: <p>I believe the question <a href="https://chess.stackexchange.com/questions/5287/how-to-start-learning-chess">How to start learning chess?</a> is actually two questions only one of which is a duplicate. This question is a fixed up version of it which asks only the other one of those questions.</p>

<p>Would it be possible to explain the rules of chess in a nutshell? A clear short description of the rules is nowhere to be found but I'm sure it can be explained very simply.</p>
 12873: <p>How to win: preventing the opponent's king from moving while attacking it. This is a <em>checkmate</em>.</p>

<p>That's the goal of the game. The rest of the rules just relate to how each piece moves.</p>

<p>King: Can move one square in any direction.</p>

<p>Queen: Can move any number of squares in any direction, but can't jump over pieces in the way.</p>

<p>Bishop: Can move any number of squares along any diagonal it's on, but can't jump over pieces in the way.</p>

<p>Rook: Can move any number of squares horizontally or vertically, but can't jump over pieces in the way.</p>

<p>Knight: Can move in an L-shape. 2 squares horizontally and one square vertically, <em>or</em> 2 squares vertically and one square horizontally. It <em>can</em> jump over any pieces in the way.</p>

<p>Pawn: Can move one square forward, and has the additional option of moving 2 squares forward if it's on its starting square. However, it captures enemy pieces by moving one square <em>diagonally</em> in either direction. The pawn is unique in that it captures and moves differently (unlike all other pieces). In addition, if the pawn reaches the end of the board it turns into a queen, rook, bishop, or knight (your choice).</p>

<p>Also, the game could end where no one wins, a tie or <em>draw</em>. This can happen in a variety of ways:</p>

<ul>
<li>Both sides only have a king left.</li>
<li>Neither side has any material left that's sufficient to possibly make a checkmate. Any example is one side having a king and knight vs a lone enemy king.</li>
<li>A position has been repeated three times. This is called a three-fold repetition.</li>
<li>One player offers a draw and the opponent accepts.</li>
<li>Stalemate: one side has no moves left because his king is trapped and the rest of his pieces have either been captured off the board or cannot move. This is very similar to a checkmate, except that the trapped king is <em>not</em> being attacked.</li>
</ul>

<p>I've left out some rules, but this is the meat of it.</p>
 4418: <p>The definitive guide to chess is given in the <a href="https://www.fide.com/fide/handbook.html?id=208&amp;view=article" rel="noreferrer">FIDE Laws of Chess</a>. The game itself is defined by the first five articles and this is short. </p>

<p>There are many more articles, appendices and even guidelines in the FIDE Laws of Chess which cover over-the-board competition rules and practices but these are not required for a basic understanding of the game, only for tournaments.</p>
