Chess Opening Theory/1. d4/1...d5/2. c4/2...e6/3. Nc3/3...Nf6/4. Nf3/4...c6/5. e3

= Semi-Slav Defence =

5.e3
The c-pawn is now protected by the light-squared bishop. The bishop can be moved later for castling. Black will usually want to try developing his dark-squared bishop to a square like b4, and castle.

Theory table
.

'''1. d4 d5 2. c4 e6 3. Nf3 Nf6 4. Nc3 c6 5. e3'''