In all the projects and explanations I will use various terms to identify the same thing.

In particular I could mention -, 0V, negative pole of the battery, ground, GND and Vss.

Those all mean the negative pole of the battery that is at 0V.

On the other side of the spectrum I mention +, Vcc, Vdd or positive pole.

This refers to the positive pole of the battery which exact value will be different depending on the battery or power source used: 9V, 3.3V, 5V, and so on.

Why so many terms? Different families of electronic components adopted different acronyms:

• TTL (Transistor-Transistor Logic) components use Vcc and GND.
• CMOS (Complementary Metal-Oxide-Semiconductor) components use Vdd and Vss).