4-2-3-1
Usually a defensive formation as it only uses one player up front. But, it is very flexible as the AML/R can either go forward and support the lone ST or drop back to create a five man midfield. Played to keep posession/slow build up/control the game, but it is also used as a good counter attacking formation
It contains a normal back for, two CM's/DM's, AML/R, AMC and ST. Depending on how you want to play the CM's can either both stay back and be strong/good tacklers etc, or you could have one DM type (De Rossi) and one more creative DM type (Pirlo). Again depending on style, fullbacks either just defend or they can go forward aswell. AMC, is very important as he is the link between the midfield and the attack. Should be creative, good passer, good decisions etc (Kaká/Diego/Riquelme type). Finally, the ST. I prefer a big, strong all-rounder up front (Drogba/Torres), but you can also play a fast striker and get it forward quicker.
Used a lot in Europe, by many teams especially Spain/France/Italy.