Simply stated..."Wake Turbulence"...is the turbulent air caused by an aircraft as it passes through air. An airliner leaves a wake through air just like a ship does through water, (waves).
This turbulent air is left behind an aircraft (in it's wake) and is mostly caused by a combination of Wingtip Vortices and other forms of Parasite Drag. Some part of this wake could be considered Jet Blast.
This air comprises of swirling eddies and twisting vortexes left behind by an aircraft's wing & body as it disturbs the air it's flying through. (while producing both Lift & Drag).
It is well known that airliners leave the most powerful / dangerous wake turbulence while they are flying "Low & Slow"...such as during final approach, when their gear and flaps are down.
Lighter aircraft should always be spaced accordingly behind larger aircraft while on final approach (2 to 4 minutes) to ensure that lighter aircraft do not suddenly encounter Wake Turbulance and experience uncommanded Roll, Pitch & Yaw of the aircraft, caused by invisible eddies of air.
I hope this starts to help. I'm sure you'll get more replies.