Define the term "fade" in barbering.

In barbering, the term "fade" refers to a haircut technique where hair gradually shortens from the top to the bottom. This technique creates a smooth transition between different lengths of hair, which can give a clean and polished appearance. The fade can vary in how high or low it starts and can be blended with different styles, providing versatility and a personalized look for the client. This gradual change in length is what distinguishes a fade from other hairstyle techniques, ensuring that the haircut has a seamless flow rather than a defined line.

The other choices do not accurately define a fade in the context of barbering. A hairstyle with a defined part does not incorporate the gradual length changes characterizing a fade. Coloring hair pertains to tinting or dying and is not related to the fading technique. Additionally, adding volume to hair typically involves techniques such as layering or using specific products, rather than the gradual shortening seen in a fade.