As far as the front wing is concerned: - the bigger, the more complicated means more downforce thus enabling drivers to go faster in a corner but such wing leads to more dangerous situations, such as puncturing oponent's tires. The bigger wings were introduced in 2009 when many parts of the cars were streamlined in order to improve overtaking and reduce dependency on aerodynamics.
The rear wing: - DRS was introduced 2 years ago. It stands for Drag Reduction System - driver can "open" rear wing to reduce drag (downforce is reduced). Basically means that rear wing is split horizontally into two smaller wings. This system improves top speed so it can be only used on straight lines. The failure of this system can lead to lost of control of the car in non-straight parts of the circuit. The usage of this system is heavily reduced by regulations.