...and why you should care
When you do different things at the same time.
Think boiling water and checking Facebook.
When you span a job over multiple workers.
Think a lot of people washing dishes.
Communication-heavy tasks
Par example Network, Disk I/O
Computation-heavy tasks
Par example Simulations, Linear Algebra
P1 is washing dishes
P2 is cooking meth
P3 has a break
P1, P2 and P3 are washing dishes... or cooking meth, whatever
Directed Acyclic Graph