What is Electric Charge?

What is electric charge? Well, there's an easy answer and a hard answer. Here is the easy answer: 

Charge is...

...the stuff that flows during an electric current.

...the stuff that appears on a balloon when you rub it on your hair.

...the stuff that comes in two kinds: positive and negative.

...charge is like mass: it's a property, but it's also like "a stuff" ...a conserved quantity

...charge is the Plus/Minus electric poles (as opposed to North/South magnetic poles.)

...it's the stuff that causes electrical forces.

...charge is the "glue" that connects all of the e-field flux onto the protons and electrons.

...charge is the positive and negative stuff that forms atoms.

...charge is the stuff that is carried by electrons, protons, positrons, and other particles.

More explanation here : http://amasci.com/elect/charge1.html