Lift and drag forces
Aerodynamic forces and moments on a body arises from two basic sources; pressure distribution and shear stress distribution over the body surface. Pressure force comes from the air whereas shear force comes due to the friction between the body and the air.
Both pressure and shear stress distribution over the complete body creates a resultant aerodynamic force R.
Lift is the component of R which is perpendicular to free stream velocity. Whereas drag is a component of R which is parallel to free stream velocity.
Lift force counteracts the weight when an aircraft is in air. Lift force is mostly generated by the wings, while there is also small contribution of rest parts of the aircraft like horizontal stabiliser and fuselage.
Drag force is a force which opposes the thrust force produced by the aircraft engines.