Squamous cells are basically types of cellss which can be identified histologically by the fact that they look flattened and thin under a microscope. They are one of the cell types which comprise an epithelium.

Epithelia lined by squamous cells can be classified as either stratified or simple. In simple squamous epithelia all the cells are in contact with the basement membrane of the epithelium whereas in stratified squamous epithelia the cells which line the epithelium are arranged in layers and as such some (most) won't be in contact with the basement membrane.

Other epithelia include columner epithelia, cuboidal epithelia and transitional epithelia.