Resistor color codes are used to represent the resistance value of resistors. Here’s a quick guide to decoding them:

1. Color Bands: Resistors typically have four or five color bands. Each band represents a digit or a multiplier.
2. First Band (1st Significant Digit):
   • The first band represents the first significant digit of the resistance
   • Color to Digit Mapping:
     • Black: 0
     • Brown: 1
     • Red: 2
     • Orange: 3
     • Yellow: 4
     • Green: 5
     • Blue: 6
     • Violet/Purple: 7
     • Gray: 8
     • White: 9

1. Second Band (2nd Significant Digit):
   • The second band represents the second significant digit of the resistance
2. Third Band (Multiplier):
   • The third band represents the multiplier, which tells you how many zeros to add to the two significant digits.
   • Color to Multiplier Mapping:
     • Black: 1
     • Brown: 10
     • Red: 100
     • Orange: 1,000
     • Yellow: 10,000
     • Green: 100,000
     • Blue: 1,000,000
     • Violet/Purple: 10,000,000
     • Gray: (some use 0.01, others use 0.1)
     • White: (some use 0.001, others use 0.01)

1. Fourth Band (Tolerance):
   • The fourth band represents the tolerance, which indicates the percentage range within which the actual resistance may vary.
   • Color to Tolerance Mapping:
     • Brown: ±1%
     • Red: ±2%
     • Green: ±0.5%
     • Blue: ±0.25%
     • Violet/Purple: ±0.1%
     • Gray: ±0.05%
     • Gold: ±5%
     • Silver: ±10%

1. Fifth Band (Temperature Coefficient – Optional):
   • Some resistors have a fifth band, which represents the temperature coefficient. It indicates how much the resistance will change with temperature.
   • Color to Temperature Coefficient Mapping:
     • Brown: 100 ppm/°C
     • Red: 50 ppm/°C
     • Orange: 15 ppm/°C
     • Yellow: 25 ppm/°C

Example:

• Let’s say you have a resistor with the colors: Red, Violet, Green, Gold.
• The first digit is 2 (Red), the second digit is 7 (Violet), the multiplier is 100,000 (Green), and the tolerance is ±5% (Gold).
• So, the resistance is 27 * 100,000 ohms with a tolerance of ±5%.

Remember, this is a basic guide. Some resistors may have additional bands for special purposes.