The microvilli (sg. microvillus) are microscopic projections in the brush border of the cellular membrane. Microvilli are encased in the plasma membrane and appear as microscopic folds in the cellular membrane.
The term microvilli is a combination of the prefix micro- and the term villus, which is derived from a Latin word that refers to a thick tuft of hair comparable to fleece.
Like the villi, who are similarly named, the microvilli are used to extend the surface area of the cellular membrane lining. This increases the space for and the productivity of transport proteins for nutrient absorption