user12730: What makes a grandmaster special? Is it the amount of steps the grandmaster can foresee, or the creativity? How many steps can a grandmaster foresee in average in a game (for instance Carlsen and Ivanchuk)? Is there a minimum amount?

user12873: It entirely depends on the position and number of variations.  For example, if there is a forced line (where both sides only have one option on each move in a line), then grandmasters can calculate 20 or 30 moves ahead without much trouble.
But if each side has multiple choices on each move, grandmasters can not calculate nearly as much, since the number of possible positions grows exponentially.  Think of the number of variations as a tree - if both sides have two choices on each move, the tree grows two new branches at each branch.  You can see how this would become very large quickly.
In general though, most positions do not require extensive calculation - on most of their moves, Grandmasters only calculate 4-5 moves ahead... mainly to just make sure their idea works.  They would only need to calculate many moves when they're in an intense tactical battle, which usually only happens once or twice in a game (since the winner of the tactical skirmish usually wins the game shortly after).
What makes a grandmaster special is a number of things.  The ability to calculate many moves is definitely one trait, but there are many other traits as well:

Evaluating a position to find the correct plan.
Pattern recognition abilities (the quickly recognize tactics or well known strategic plans during a game).
Raw talent - many people work very hard at the game, but only 0.1% of those people actually make it to grandmaster level.
Competitive spirit and the will to win - this one is definitely important in competitive tournaments.  The burning desire to win is important to succeed in chess, even though it may be somewhat unhealthy to have in real life :)


user-1: It depends upon the position. 
For a simple endgame, grandmasters use shortcuts to see very far. For example, using the rule of the square, a grandmaster can see 7 moves. Combining other shortcuts like this, they can see 15 or more moves ahead.
In middlegames with few tactics, GM Soltis argued in Studying Chess Made Easy that seeing 2 1/2 moves ahead was sufficient for grandmasters to find a good move.

user11629: This depends a lot on the position and cannot be answered generally. If you have a forced line, i.e. a position where there are only few candidate moves at every step, a grandmaster can calculate many moves. I am reluctant to give a concrete number because it really depends, but to give you a rough idea, let's say 20 moves.
On the other hand if the position is rather closed, of the maneuvering type, with many equal alternatives at every step, the calculation depth will be much smaller, simply because the number of variations will be much much larger in this case. And even if you calculated 20 moves deep you might not come to a conclusion on which line is best, because 20 moves in the future the position might still be equal. In this case a grandmaster would typically only calculate a couple of moves deep (if at all) in order to check that he is not blundering anything to a tactic.
As you can see from this description, pure calculation strength is only needed sometimes in a game and certainly not the only reason that grandmasters are much better than the rest. Unlike computers, humans do not play chess by calculating many moves in advance. The strength of human players over computers is that they can evaluate the position and develop a plan based on the evaluation. Humans focus more on recognizing patterns and play moves based on these patterns.
So, grandmasters are grandmasters, because they are good at all parts of the game:

calculating many moves ahead
evaluating a position correctly
finding the right plan
good at defense: using tactical ideas, standard methods, pure calculation...)
good at openings: knowing main lines, side lines, recognizing wrong moves in an opening and knowing how to react to them, knowing the ideas behind openings...
good at endgames: as with openings, there is a huge body of theory that you can study; also some grandmasters like Carlsen, are said to be particularly good at endgames beyond the known theory
pattern recognition abilities: to recognize tactics and other known motives
creativity
personal traits, physical fitness


12730: <p>What makes a grandmaster special? Is it the amount of steps the grandmaster can foresee, or the creativity? How many steps can a grandmaster foresee in average in a game (for instance Carlsen and Ivanchuk)? Is there a minimum amount?</p>
 12873: <p>It entirely depends on the position and number of variations.  For example, if there is a forced line (where both sides only have one option on each move in a line), then grandmasters can calculate 20 or 30 moves ahead without much trouble.</p>

<p>But if each side has multiple choices on each move, grandmasters can not calculate nearly as much, since the number of possible positions grows exponentially.  Think of the number of variations as a tree - if both sides have two choices on each move, the tree grows two new branches at each branch.  You can see how this would become very large quickly.</p>

<p>In general though, most positions do not require extensive calculation - on most of their moves, Grandmasters only calculate 4-5 moves ahead... mainly to just make sure their idea works.  They would only need to calculate many moves when they're in an intense tactical battle, which usually only happens once or twice in a game (since the winner of the tactical skirmish usually wins the game shortly after).</p>

<p>What makes a grandmaster special is a number of things.  The ability to calculate many moves is definitely one trait, but there are many other traits as well:</p>

<ul>
<li>Evaluating a position to find the correct plan.</li>
<li>Pattern recognition abilities (the quickly recognize tactics or well known strategic plans during a game).</li>
<li>Raw talent - many people work very hard at the game, but only 0.1% of those people actually make it to grandmaster level.</li>
<li>Competitive spirit and the will to win - this one is definitely important in competitive tournaments.  The burning desire to win is important to succeed in chess, even though it may be somewhat unhealthy to have in real life :)</li>
</ul>
 -1: <p><strong>It depends upon the position</strong>. </p>

<p>For a simple endgame, grandmasters use shortcuts to see very far. For example, using the <a href="https://en.wikipedia.org/wiki/King_and_pawn_versus_king_endgame#Rule_of_the_square" rel="noreferrer">rule of the square</a>, a grandmaster can see 7 moves. Combining other shortcuts like this, they can see 15 or more moves ahead.</p>

<p>In middlegames with few tactics, GM Soltis argued in <em>Studying Chess Made Easy</em> that seeing 2 1/2 moves ahead was sufficient for grandmasters to find a good move.</p>
 11629: <p>This depends a lot on the position and cannot be answered generally. If you have a forced line, i.e. a position where there are only few candidate moves at every step, a grandmaster can calculate many moves. I am reluctant to give a concrete number because it really depends, but to give you a rough idea, let's say 20 moves.</p>

<p>On the other hand if the position is rather closed, of the maneuvering type, with many equal alternatives at every step, the calculation depth will be much smaller, simply because the number of variations will be much much larger in this case. And even if you calculated 20 moves deep you might not come to a conclusion on which line is best, because 20 moves in the future the position might still be equal. In this case a grandmaster would typically only calculate a couple of moves deep (if at all) in order to check that he is not blundering anything to a tactic.</p>

<p>As you can see from this description, pure calculation strength is only needed sometimes in a game and certainly not the only reason that grandmasters are much better than the rest. Unlike computers, humans <strong>do not</strong> play chess by calculating many moves in advance. The strength of human players over computers is that they can <em>evaluate</em> the position and <em>develop a plan</em> based on the evaluation. Humans focus more on recognizing patterns and play moves based on these patterns.</p>

<p>So, grandmasters are grandmasters, because they are good at all parts of the game:</p>

<ul>
<li>calculating many moves ahead</li>
<li>evaluating a position correctly</li>
<li>finding the right plan</li>
<li>good at defense: using tactical ideas, standard methods, pure calculation...)</li>
<li>good at openings: knowing main lines, side lines, recognizing wrong moves in an opening and knowing how to react to them, knowing the ideas behind openings...</li>
<li>good at endgames: as with openings, there is a huge body of theory that you can study; also some grandmasters like Carlsen, are said to be particularly good at endgames beyond the known theory</li>
<li>pattern recognition abilities: to recognize tactics and other known motives</li>
<li>creativity</li>
<li>personal traits, physical fitness</li>
</ul>
