An "Effects Loop" is a feature found in many guitar amplifiers that allows musicians to connect effects pedals between the preamp and power amp sections. This setup enables the use of effects, such as reverb or delay, after the amplifier's tone shaping, resulting in a clearer and more defined sound. Using an effects loop can enhance the overall tone by preserving the integrity of the original signal. It allows for better control over the effects, as they can be applied to the amplified signal rather than the raw guitar signal, leading to a more polished and professional sound in live performances or recordings.