Resistors will probably be in every analog circuit you ever build, and are a crucial piece in virtually every analog and digital device you've ever used. They have one characteristic, called resistance.

Simply put, resistance reduces the current flowing through a circuit. More resistance, less current, and vice versa.

Very soon we'll get into how this works mathematically, with a surprisingly simple formula you may have already heard of called Ohm's Law. As you get further and further into circuits you'll see how Ohm's Law never stops being useful, and simple, however complex the other parts of your circuits get.

For now, I'm just going to show you how to measure a resistor, which you'll need for the upcoming Breadboards lesson. We'll get into Ohm's Law and other resistance-related topics soon after, in their own upcoming lessons.

Resistance is measured in ohms, which is also denoted by the Greek omega symbol Ω.

An ohm is a very small amount of resistance. We'll mostly be working with resistors in the kilohms - thousands of ohms. 1 kilohm = 1000 ohms.

People typically just write the letter k instead of kilohms. You'll also sometimes see kΩ.

So 1k = 1kΩ = 1 kilohms = 1,000Ω = 1,000 ohms.