Jiva means "soul" in Jainism, and is also called jivatman. It is a core concept and the fundamental focus of the Jain theology. The soul is believed to be eternal, and a substance that undergoes constant modifications, in every life, after every rebirth of a living being. Jiva consists of pure consciousness in the Jain thought, has innate "free will" that causes it to act but is believed to be intangible and formless. It is the soul that experiences existence and gains knowledge, not mind nor body both believed to a heap of matter. Jain philosophy further believes that the soul is the mechanism of rebirth and karma accumulation. It is the same size in all living beings, such as a human being, a tiny insect and a large elephant. Jiva is everywhere, filling and infused in every minuscule part of the entire loka (realm of existence), according to Jainism. The soul has the potential to reach omniscience and eternal bliss, and end the cycles of rebirth and associated suffering, which is the goal of Jain spirituality.
According to Jain philosophy, this universe consists of infinite jivas or souls that are uncreated and always existing. There are two main categories of souls: un-liberated mundane embodied souls that are still subject to transmigration and rebirths in this  samsara  due to karmic bondage and the liberated souls that are free from birth and death. All souls are intrinsically pure but are found in bondage with karma since beginning-less time. A soul has to make efforts to eradicate the karmas attain its true and pure form.
10th-century Jain monk Nemichandra describes the soul in Dravyasamgraha:
The qualities of the soul are chetana (consciousness) and upyoga (knowledge and perception). Though the soul experiences both birth and death, it is neither really destroyed nor created. Decay and origin refer respectively to the disappearing of one state and appearing of another state and these are merely the modes of the soul. Thus Jiva with its attributes and modes, roaming in samsara (universe), may lose its particular form and assume a new one. Again this form may be lost and the original acquired.
Jivas are believed to be of two types: stationary and mobile. Illustration of the former are plants, while moving jivas include examples such as human beings, animals, gods, hell beings and insects. Jivas are further classified in Jain philosophy by an assigned number of senses which range from one to five sensory organs. Inert world such as air, fire or clod of dirt, considered non-sensate in contemporary science, are asserted in historic texts of Jainism to be living and with sensory powers.