How do resistor color codes work?

4-band resistors: Band 1 = first digit, Band 2 = second digit, Band 3 = third digit (for 5-band; or multiplier for 4-band), Multiplier band, Tolerance band. Colors: Black=0, Brown=1, Red=2, Orange=3, Yellow=4, Green=5, Blue=6, Violet=7, Gray=8, White=9. Gold multiplier=×0.1, Silver=×0.01.

How do I read a resistor color code?

Example: Brown-Black-Red-Gold: 1-0-×100-±5% = 1,000Ω (1kΩ) ±5%. Another: Red-Violet-Orange-Gold: 2-7-×1000-±5% = 27,000Ω (27kΩ) ±5%. Tolerance band spacing is wider than others. Silver and gold are ONLY tolerance/multiplier bands — they never appear as digit bands.