A frequency comb is a tool used in precision measurement of light frequencies. It consists of a series of equally spaced sharp peaks in the frequency spectrum, resembling a comb. This unique structure allows scientists to measure and compare different wavelengths of light with high accuracy, making it valuable in fields like metrology and spectroscopy. Frequency combs are often generated using mode-locked lasers, which produce short pulses of light. Each pulse corresponds to a specific frequency, creating the comb-like pattern. These devices have applications in various areas, including telecommunications, atomic clocks, and chemical analysis.