The Carlsbad pawn structure is one of the most common pawn structures in chess, and it looks like this: 



This structure arises from the Exchange Queen's Gambit Declined - with 1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.cxd5 exd5 5.Bg5 being the most common example. (If you'd like to know a creative alternative to s...