So we’ll start with the wikipedia definition again. Current is the “flow of electric charge through an electric conductor.” Let’s refer back to our water analogy that we started in the voltage episode of multimeters. We said that the voltage was analogous to the pressure that a pump could provide to a water system. How fast the water actually flows through the pipes would be analogous to current flow. Again, we’re not going for deep academic understanding of this stuff although if you want to, more power to you. We just need to know enough to get our projects off the ground. So think of current as how fast electricity is flowing through your wires and into your circuit.
As with voltage, current has two flavors: AC and DC. DC is primarily what we’ll be messing with and stands for “direct current”. Just as a DC voltage is always “on” a DC current is always “flowing.” It doesn’t necessarily always have to flow at the same rate but it will always flow in the same direction. It’s easiest just to remember that current flows from high voltage to low voltage. More specifically, it will always try to flow to ground and will take the path of least resistance.
As with AC voltage, AC current will change direction. It doesn’t always flow in one direction. It will constantly switch directions from positive to negative and back to positive.
Remember that measuring current is different from measuring voltage. You don’t just put the probes on different points of your circuit. You always have to measure current inline. Remember it’s like you’re trying to figure out how fast the water is flowing through your pipes so you have to actually interrupt your circuit and hook up inline.