What a Drag

Drag is the resistance of an object to moving through the air. 
There are two main types of drag:

INDUCED DRAG
Induced drag is a by-product of producing lift.
Induced drag decreases with velocity.
It increases with weight and altitude (for a given speed)
It increases whenever the AOA increases.
It is related to the design of the wing and can be reduced by high aspect ratios and winglets.

PARASITE DRAG
All objects feel parasite drag when moving through a fluid.  
Parasite drag increases with velocity.
It decreases with altitude.
It is not affected by changes in AOA.
There are three types of parasite drag:

• Skin Friction: friction between air and surface of object
• Form Drag: drag resulting from air moving around a particular shape (i.e. is it streamlined?)
• Interference Drag: flows over two joined surfaces interfere with each other (i.e. wing and fuselage)