Bogo-Indian Defense: Retreat Variation

What Is The Retreat Variation?

The check on move three asks White a question, and 4.Bd2 answers it. You retreat to e7, keeping every piece on the board, and leave White's bishop stranded on d2, where it blocks the queen and attacks nothing. The famous point of the Retreat Variation is that both sides have spent a tempo on a bishop move, but your bishop stands on its best square and White's stands on its worst.

From here, play d5 for a solid Queen's Gambit structure, or d6 followed by e5. White needs Nc3 and e4 to claim the center, and that is where games are decided: strike back with c5 or e5 before the big center rolls forward, and White is left defending loose pawns with a bishop that never joined the game.