Why do some common openings move a pawn in front a bishop prior to moving the king's or queen's pawn?

Question

I've seen several people do this and assumed it was a beginner's mistake (since I'm a beginner myself and I play on the chess.com app usually only against other players within 25 points of my rating), especially since, going through game reviews, the engine usually shows those opening moves as giving less of an advantage than moving the king or queen's pawn to make room for the bishop's to develop and take space in the center.

But I was just reading this chess.com article on popular modern openings and several of the specific openings they look at, such as the Nasdorf variation of the Sicilian defense, involving moving a pawn on the b or c file prior to even developing the knights or bishops. And these are all presented as perfectly valid openings.

But I don't understand. Unless it's to defend against an immediate attack, why move those pawns instead of immediately both grabbing space in the center and preparing a bishop for development by moving the king or queen's pawn? What's the potential benefit?

Answer 1

First off: please use algebraic notation to denote moves. This will not only help whoever is answering you to better understand your question but also yourself because it is the common way to describe moves or variations in chess. Think of being proficient in using this form of notation as analogous to knowing how to read sheet music for a musician or being able to read for a writer.

To your question itself:

Consider a position like after 1.e4 e5. Obviously white wants to increase his influence in the center and the go-to plan is to remove the pawn on e5 somehow. One possibility for this is to play f4 so that either white will take/exchange in the next move or black has to take himself and then the pawn is no longer on e5 - mission accomplished.

Now, to play f4 (or, in case of 1. d4 d5, the move c4, with the same motivation) the respective knight (g1 or b1) must not be moved before, because it would go to f3 (or c3) thus blocking the pawn. Therefore, one plays f4 or c4 before moving the knight.

There are openings where this is done immediately:

• 1. e4 e5 2. f4!? is called the Kings Gambit
• 1. d4 d5 2. c4 is called the Queens Gambit
• 1. c4 is called the English opening and its justification is that white doesn't have to decide if he plays d4 (arriving in the queens gambit) or not, thus remaining a bit more flexible.

For blacks play analogous motivations apply.