What is yellow circle on match?

A yellow circle on a match refers to the striking pad or head of the matchstick. It is a circle made of a friction material that helps ignite the match when rubbed against it. The yellow color is usually used to make it more visible and easily distinguishable from the rest of the matchstick. The circle is sometimes coated with small amounts of igniting chemicals like red phosphorous or antimony sulfide to make it ignite easily.