[tdeck]

Everyone is giving correct answers so I'll just add something: in some parts of the world the convention has been to consider current flowing from negative to positive. For example in Scotland it's often taught that way apparently: https://www.mrsphysics.co.uk/blog/why-electron-flow-scotland...

I read somewhere that this was also common in the USSR but can't find any references. Perhaps someone here will remember.

[pwg]

From reverse engineering a few low cost Chinese imports (i.e., the 'odd brand names one finds on Amazon') I discovered that some Chinese engineers also design electronics using the convention of current flow from negative to positive.

[speakeron]

How can you tell from analysis of the physical circuit what assumptions the designer made about the flow of current? Surely the components (electrolytic capacitors, diodes, transistors, etc) are the same and can only work in one direction. Is it that the ground plane is connected to the positive terminal of the power supply?