Final answer:
Needles are color coded to indicate their gauge, which refers to the thickness of the needle and is important in medical procedures.
Step-by-step explanation:
The color coding of needles is used to indicate their gauge. The gauge refers to the thickness of the needle and is an important factor in medical procedures. Different gauges are used for different purposes, such as drawing blood or administering injections. For example, a larger gauge needle may be used for collecting blood samples, while a smaller gauge needle may be used for injecting medication.