The idea is to get the rook off the unpleasant diagonal and support the future c7-c5 push.
1. d2d4  1... d7d5  2. c2c4  2... e7e6  3. g1f3  3... g8f6  4. g2g3  4... f8e7  5. f1g2  5... e8g8  6. e1g1  6... d5c4  7. d1a4 7.Qc2 is the most popular move. The idea of the move played is to avoid 7...b5. 7... a7a6 The downside is that now White cannot play 8.a4, an option that is possible when the queen is on c2. 8. a4c4  8... b7b5  9. c4c2  9... c8b7  10. c1d2  10... b7e4  11. c2c1 One of the most important positions in the Catalan Opening, with thousands of games. 11... b8c6  12. d2e3 Defending the d-pawn and preparing to develop the knight on d2.