Caves are geological wonders evolved from rock weathering followed by erosional process. Dark nature creates a unique environment where extreme conditions are prevailed. Diverse terrain conditions results in assorted morphologies both internally and externally, forming characteristic cave formations. Most of the caves have been originated in limestone land masses but also evolved in silicate terrains. Hence, bed rock geology uniquely forms the caves with different sizes and shapes, in addition to the support given by structural diversity of terrain geology. Massive caves have been evolved in carbonate terrains and the various cave formations known as speleotherms are also common in such carbonate caves rather than that of rarely found in silicate caves. Breakdown piles deposited on cave grounds account for cave sediments which are composed of aeolian sediments and biological components. The cave sediments are characteristically rich in organic matter; hence it contributes in climate change mitigation. Diverse chemistry of cave sediments supports extremophiles in dark caves while rock eating bugs are also facilitated. Either habitable or inhabitable caves have been accessed for a long period of time by prehistoric and ancient people. Hence archaeologically cave have been studied extensively to extract the evidences of human evolution.