Also, a note regarding the direction of flow, in a circuit.
It's really arbitrary. And, there are two conventions [because it's arbitrary]. The important thing is:
Pick a convention and stick to it throughout a discussion/project. It also helps if everyone knows which convention was chosen, and is onboard with consistent compliance with that convention.
The two conventions are:
- Electron flow -- [From negative to positive] -- typically chosen by Physicists and Technicians
- Conventional Flow -- [from positive to negative] -- typically chosen by Engineers -- fun fact: this convention was established by Ben Franklin -- 'cuz he thought that was how "juice" flowed. It can be thought of as a flow of "charge" -- Another fun fact: the arrow on a Diode points to the direction of Conventional Flow.
Why is it arbitrary? Because, in terms of designing circuits, it really doesn't matter which way the current flows. Truly, in the world of Physics, where the mechanism is king, it does matter, but, unless you're designing Atom Smashers, why fuss about it?
Not sure what's up with technicians, though -- maybe it's about being contrary, like how the rest of the world drives on the Left side of the road 
I prefer conventional flow, because then the diode symbols make sense -- and negative ground is easier to deal with