[Azimov]

mA and A are the same thing. Just a different level of measuring current. Like inches and feet. 1000mA is equal to 1A. 500mA is the same as saying .5 A. They are both measured by time. Hence the h at the end of many spec write ups. Why it is called miliAmps rather than kiliAmps as in Ohms is beyond me.
Current flows, just like water. The way you measure it is how much flows past a given point in a certain amount of time. Again, just like water flowing over a dam. Voltage is pressure. Or, how much force is applied to pushing the water over the dam. Which is why when you raise voltage (pressure) more current can flow over the dam faster. And resistance is holding the current back, like the dam itself. If you lower the top of the dam, at a given pressure, more current flows due to less resistance, raise the dam until no current flows and you are said to have maximum resistance or no current flow. Materials with this property are called insulators. This water analogy works well for me as electrons in a wire behave the same way as water molecules in a pipe. Not really though, it's like saying the sun sets and rises rather than the earth going around the sun causing the illusion of the sun moving. When water flows into a pipe, the same water molecules flow out the other end. In a wire, electrons smack into one another like those executive desk toys that bang steel balls together. The first one strikes the next and so on until the last one pops out of the wire to feed your circuit. I'ts not the original electron that you pumped into the wire. This is why copper is such a good conductor. It has more free electrons to supply this chain reaction. It's also why it's so soft. Gold is the best conductor for the same reasons.