Chess Opening Theory/1. d4/1...Nf6/2. c4/2...c5/3. d5/3...b5

= Benko Gambit = Black offers the b5 pawn in return for a slight lead in development and a superior pawn structure. The main idea is that Black gets strong positional pressure against White's queenside, where they have two open files for his rooks (after ...a6), and an open diagonal for the fianchetto on g7. The pawn structure has lasting effect and often even if White enters the endgame up a pawn, they will find it hard to convert this advantage into a win. As theory has developed, however, it's become harder for Black to find lines with winning chances and with proper play white can usually weather the storm.

Theory table
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'''1. d4 Nf6 2. c4 c5 3. d5 b5'''