Knee-high boots are boots that rise to the knee, or slightly thereunder. They are generally tighter around the leg shaft and ankle than at the top. Originally made of leather, versions made of a synthetic rubber (PVC, Neoprene, etc.), they are used by fishermen, dairy workers, stable hands, duck hunters, clammers, etc. to protect the feet from water, mud, manure, etc. and to provide traction on slippery surfaces. Most slip on, but there are varieties with buckles and those that lace up.

Knee-high boots are used in the fashion world since at least the 1950s. The fashion boot article discusses this in depth.

Most popular fashion knee-high boots are flat boots, low heeled boots, heel boots, & platform boots. Boots are versatile, and people can wear them with multiple outfit options.