In a three-band resistor, the first two bands represent the first two significant digits followed by one band for the multiplier. It is always better to check the manufacturer’s documentation or use a multimeter to get the exact resistance value. If a gold or silver band is present, then they must be at the right end since they are never used for significant digits. A larger gap between the tolerance band and the other bands is sometimes noticeable. To distinguish the reading direction, the tolerance band width is sometimes printed with 1.5 - 2 times the width of other bands. The reading direction is not always clear. Resistors cases usually have three to six bands that indicate their resistance, tolerance and sometimes their temperature coefficient of resistance (TCR).
It describes the coding standard for both resistors and capacitors.
The coding is defined in the international standard IEC 60062:2016. Surface mounted resistors (SMD) use another coding system that uses alphanumeric codes printed on its surface instead of color codes. When the resistor body surface is large enough, as in large wattage resistors, the resistance value, tolerance, and wattage are usually printed on the body of the resistor. Color-coding is also used for capacitors, inductors and diodes. Color bands are used because they can be easily and cheaply printed on a small electronic component.