Let’s start with a quote.
“When a fluid is both frictionless and irrotational, pleasant things happen” – F.M White
The Potential Flow or velocity potential exists as the velocity field as the gradient of a scalar function. If a flow is irrotational, then its curl will equate to zero, and if a flow is incompressible, then its divergence of velocity will equal zero. We use a flow that consists of both of these to
When thinking about potential flow, I found this video extremely useful and informative.
I liked this topic as it is a very practical vision of how fluid work.
References
My Fluid Dynamics Blog 