Williams is a type of pear that's native to Europe and it was discovered in Aldermaston, England, in 1765 by a schoolmaster named Mr. Stair, but a nurseryman named Williams acquired the variety later and introduced it to the rest of the country, hence the name.
In the United States, the same pear is known as the Bartlett. The pears are medium to large and they have thin skin that transforms from green to golden yellow as it ripens. The flesh is fine-grained, smooth, and juicy in texture, while the flavor is aromatic, tart, buttery, and sweet when fully ripe.