Step 1: What They Are
The different colors on the resistor tell the resistance (in ohms) and the tolerance (in %).
They also have different power ratings measured in (watts).
To read the resistor you read it from left to right, resistors have four bands. Usually the tolerance reading has a bigger gap from the other 3 the third band is the multiplier and the first two are the first numbers. E.g. If the resistor is Brown,Black,Brown and Gold the resistor is 100 ohms @5% tolerance.
Any resistor with a resistance of 1000 ohms and greater usually is abbreviated with the letter "K". For example 1000 ohms = 1K.
And resistors with a resistance over a million are abbreviated with the letter "M". For example 1.000.000 ohms = 1M.
A resistor consists of a resistive film and a spiral groove.