Ruy Lopez: Exchange Variation, Keres Variation

In the Ruy Lopez: Exchange Variation, Keres Variation, the move e4 by White serves as the foundation for future attacks and controlling of the center. It also liberates the bishop on c1, allowing it to be developed and activated. Additionally, it opens up avenues for the queen and knight to enter the game, creating more opportunities for White to put pressure on Black.

By playing e5 in response to White's e4, Black immediately stakes a claim to the center of the board and helps to control important squares. This move also opens up avenues for Black's light squared bishop and queen to be developed. Additionally, it sets the stage for potential attacks on the white pieces, as Black now has more space and mobility in the center of the board.

Playing Nf3 by White after 1.e4 e5 allows White to control the important square at d4, which is crucial for central control. This move also develops a knight towards the center of the board, and opens up possibilities for the queen and bishop to be developed. Furthermore, this move threatens the f7 pawn, which is often a weak spot in Black's pawn structure, forcing Black to defend it and potentially giving White time to further develop their pieces.

In the Ruy Lopez: Exchange Variation, Keres Variation, Black's move Nc6 serves several purposes. Firstly, it attacks White's central pawn on e4, and prepares to secure Black's own control over d4. Additionally, it develops a piece towards the center of the board, which is often a key goal in the opening. This move also allows the d7 pawn to be developed, freeing up the bishop on c8. Finally, this move defends the e5 pawn, which is crucial to Black's control of the center of the board.

White's move Bb5 in response to 1.e4 e5 2.Nf3 Nc6 is the beginning of the Ruy Lopez opening. This move attacks the knight on c6 and forces Black to make a decision on how to respond. Additionally, it pins the knight to the king, which limits Black's options for defending it. This move also develops the bishop towards the center of the board, and puts pressure on Black's pawn structure. Finally, this move prepares to castle kingside, which is often a key goal in the opening for maintaining the safety of White's king.

Black's move a6 in response to 1.e4 e5 2.Nf3 Nc6 3.Bb5 is often referred to as the Morphy Defense in the Ruy Lopez opening. This move has several purposes. Firstly, it prevents the white bishop from pinning the black knight to the king. It also prepares to develop the dark-squared bishop to a7, where it can control important central squares. Additionally, this move prevents any potential threats via b5 from the white queen or knight in the future. Finally, this move secures the b5 square so that Black can use it to retreat the knight, if necessary.

In the Ruy Lopez: Exchange Variation, Keres Variation, White's move Bxc6 after 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 is the Exchange Variation of the Ruy Lopez opening. By exchanging bishops, White creates a doubled pawn structure for Black, which can weaken Black's pawn protection. Additionally, this move opens up lines for the queen and knight to enter the game. Moreover, it leads to a simplified position, which can be easier for less experienced players to manage. Finally, this move can give White a slight lead in development, as Black must spend an additional move to recapture on c6.

Black's move dxc6 in response to 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Bxc6 is a forced recapture due to the exchange variation. This move not only recaptures the captured pawn, but it also allows Black's d-pawn to be developed. However, it also results in a doubled pawn for Black, which can limit their pawn structure. Additionally, it opens up the c-file for both rooks, which can lead to potential pressure against White's pawns or pieces. Finally, this move simplifies the position further, reducing the amount of pieces on the board and potentially leading to an endgame situation.

White's move Nc3 in response to 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Bxc6 dxc6 aims to develop a knight towards the center of the board while maintaining control over important central squares, especially d4. This move also defends the e4 pawn, which is attacked by Black's dxc6 move. Additionally, this move prepares to castle kingside, bringing White's king to safety. It also allows the b1-knight to be developed and sometimes for the white queen to occupy the c2 square, creating additional pressure on Black's pawn structure. Finally, this move completes White's development, allowing them to begin focusing on the strategic plan of the game.