1.d4 d5 2.c4 - See Queen's Gambit.
2...c6 - Slav Defense. Black supports d5 while keeping the bishop on c8 active.
White's plans: Play Nf3 and e3. Exchange on d5 or develop naturally.
Black's plans: Develop ...Nf6 and ...Bf5 or ...Bg4. Castle and look for ...c5.
Watch the moves to understand the opening sequence. Use the controls to replay or auto-play the variation.