user5691: I would like to know why some openings are called "defences" and other all called "openings." What is the difference?

user17: A "defense" is a subset of an "opening." It is a system for Black against standard opening moves such as d4 or e4. Examples are the French Defense (e6) and Sicilian Defense (c5), in response to e4, where Black actively tries to take the initiative away from White.
Other "openings" are named from White's point of view, such as Ruy Lopez (following e4) or the Colle System (following d4). These are systems where Black more or less follows White's lead instead of making an "active" defense like the ones mentioned above.

user9684: The difference is whose move defined the opening.
If, after 1. e4, black responds with e6, the opening is defined as a French Defense.  If, after 1. e4 e5, white plays Bc4, the opening is defined as the Bishop's Opening.  However the most common openings, such as the Queen's Gambit, aren't considered either an opening or a defense.  (Note:  The Sicilian Defense breaks this rule, but it's variations are often so well known that we refer to them as the opening name instead of a variation.  Most people call it the Najdorf, but the Morphy variation of the Ruy Lopez would be a rarity.)

user291: "The opening", in general, is the first phase of a game of chess, in which both sides develop their pieces. It is followed by "the middlegame" and, if the game gets that far, "the endgame".
When people talk about "an opening", they are referring to a particular series of opening moves that has a name. For example, 1.d4 d5 2.c4 e6 is the Queen's Gambit Declined, and 1.d4 d5 2.c4 dxc4 is the Queen's Gambit Accepted.
Openings that are defined by the moves that Black makes are often called "defenses", since White is generally considered the attacker and Black the defender by default. For example, 1.e4 c5 is the Sicilian Defense and 1.e4 e6 is the French Defense.

5691: <p>I would like to know why some openings are called "defences" and other all called "openings." What is the difference?</p>
 17: <p>A &quot;defense&quot; is a subset of an &quot;opening.&quot; It is a system for Black against standard opening moves such as d4 or e4. Examples are the French Defense (e6) and Sicilian Defense (c5), in response to e4, where Black actively tries to take the initiative away from White.</p>
<p>Other &quot;openings&quot; are named from White's point of view, such as Ruy Lopez (following e4) or the Colle System (following d4). These are systems where Black more or less follows White's lead instead of making an &quot;active&quot; defense like the ones mentioned above.</p>
 9684: <p>The difference is whose move defined the opening.</p>
<p>If, after 1. e4, black responds with e6, the opening is defined as a French Defense.  If, after 1. e4 e5, white plays Bc4, the opening is defined as the Bishop's Opening.  However the most common openings, such as the Queen's Gambit, aren't considered either an opening or a defense.  (Note:  The Sicilian Defense breaks this rule, but it's variations are often so well known that we refer to them as the opening name instead of a variation.  Most people call it the Najdorf, but the Morphy variation of the Ruy Lopez would be a rarity.)</p>
 291: <p>"The opening", in general, is the first phase of a game of chess, in which both sides develop their pieces. It is followed by "the middlegame" and, if the game gets that far, "the endgame".</p>

<p>When people talk about "an opening", they are referring to a particular series of opening moves that has a name. For example, 1.d4 d5 2.c4 e6 is the Queen's Gambit Declined, and 1.d4 d5 2.c4 dxc4 is the Queen's Gambit Accepted.</p>

<p>Openings that are defined by the moves that Black makes are often called "defenses", since White is generally considered the attacker and Black the defender by default. For example, 1.e4 c5 is the Sicilian Defense and 1.e4 e6 is the French Defense.</p>
