user13565: Inspired by this question: when should one play Bxc6, capturing the Knight, in Ruy Lopez?
Related, but hopefully not a duplicate: this question, but it focusses on why Bxc6 isn't a popular move, while I ask what factors and ideas to consider while making the move.
To elaborate
In the early stages of Ruy Lopez, Black's Knight is en prise for several moves and White's Bishop can capture it. However, this capture sometimes occurs and sometimes doesn't.
I haven't found a clear reason why White sometimes makes the capture and sometimes doesn't. It would help to know the what factors to consider before making the move.
In short
I'd like to know the general ideas and motivating factors behind the capture (Bxc6), and when to, as well as when not to, make the capture (as White).

user13012: 4 Bxc6 became popular after Fischer made extensive use of it. He followed up with 5.O-O and although this is no longer fashionable at GM level, a lot of lesser players are uncomfortable. White can choose to develop an attack against the King (because the center is closed to counterattacks)  or play for a favorable ending, and can keep the options open for quite a long time. So, if you have Black, do you seek exchanges to avoid the attack, or do you decline the exchanges to avoid the ending? You constantly have to make that choice. The variation with 5.d4 usually leads directly to a Queen trade (5.d4 exd 6.Qxd4 Qxd4 7. Nxd4 and is played if White definitely wants the ending.
The point about Bxc6 is not that it gains a large advantage, but that White gets to decide what sort of game it will be. Those doubled Pawns are not weak, because they are hard to attack, but they make it very difficult for Black to create a passed Pawn. If you feel at ease in the resulting positions and if you study typical plans, then Bxc6 can almost always be a good move. However, the game that results is often dry and technical, so you had better enjoy that kind of thing.
I recall what Blackburne said about opening with 1.c4 "I do not play this because I like it, but because my opponent likes it less."

user14202: It is just a matter of taste.  There are pluses and minuses to the move, but the strategic idea is gaining a better pawn structure.
I have played the Exchange 4.Bxc6; the Deferred Exchange 4.Ba4 Nf6 5.Bxc6; and the Double-Deferred Exchange 4.Ba4 Nf6 5.0-0 Be7 6.Bxc6.  All have unique flavors and Black has to know the ideas in each or risks a very bad game.
The Exchange variation was used with success by Fischer.  

13565: <p>Inspired by <a href="https://chess.stackexchange.com/q/19734/13565">this question</a>: when should one play Bxc6, capturing the Knight, in Ruy Lopez?</p>
<p><strong>Related</strong>, but hopefully not a duplicate: <a href="https://chess.stackexchange.com/q/239/13565">this question</a>, but it focusses on why Bxc6 isn't a popular move, while I ask what factors and ideas to consider while making the move.</p>
<h3>To elaborate</h3>
<p>In the early stages of Ruy Lopez, Black's Knight is en prise for several moves and White's Bishop can capture it. However, this capture sometimes occurs and sometimes doesn't.</p>
<p>I haven't found a clear reason why White sometimes makes the capture and sometimes doesn't. It would help to know the what factors to consider before making the move.</p>
<h3>In short</h3>
<p>I'd like to know the general ideas and motivating factors behind the capture (Bxc6), and when to, as well as when not to, make the capture (as White).</p>
 13012: <p>4 Bxc6 became popular after Fischer made extensive use of it. He followed up with 5.O-O and although this is no longer fashionable at GM level, a lot of lesser players are uncomfortable. White can choose to develop an attack against the King (because the center is closed to counterattacks)  or play for a favorable ending, and can keep the options open for quite a long time. So, if you have Black, do you seek exchanges to avoid the attack, or do you decline the exchanges to avoid the ending? You constantly have to make that choice. The variation with 5.d4 usually leads directly to a Queen trade (5.d4 exd 6.Qxd4 Qxd4 7. Nxd4 and is played if White definitely wants the ending.</p>

<p>The point about Bxc6 is not that it gains a large advantage, but that White gets to decide what sort of game it will be. Those doubled Pawns are not weak, because they are hard to attack, but they make it very difficult for Black to create a passed Pawn. If you feel at ease in the resulting positions and if you study typical plans, then Bxc6 can almost always be a good move. However, the game that results is often dry and technical, so you had better enjoy that kind of thing.</p>

<p>I recall what Blackburne said about opening with 1.c4 "I do not play this because I like it, but because my opponent likes it less."</p>
 14202: <p>It is just a matter of taste.  There are pluses and minuses to the move, but the strategic idea is gaining a better pawn structure.
I have played the Exchange 4.Bxc6; the Deferred Exchange 4.Ba4 Nf6 5.Bxc6; and the Double-Deferred Exchange 4.Ba4 Nf6 5.0-0 Be7 6.Bxc6.  All have unique flavors and Black has to know the ideas in each or risks a very bad game.
The Exchange variation was used with success by Fischer.  </p>
