Jain epistemology classifies knowledge into five types, arranged in an ascending order of directness and completeness, and kevala jnana is defined as the fifth and final member of the series rather than as a stand-alone category, which is why Jain philosophical texts introduce it only after setting out the other four.
Mati jnana, sensory and mental knowledge, is ordinary cognition through the senses and the mind, including perception, memory, recognition and inference; it is mediate and fallible. Shruta jnana, scriptural or testimonial knowledge, is knowledge derived from words, symbols and the teaching of others, including the study of Jain scripture itself, and depends on mati jnana as its basis, since words must first be perceived and understood. These first two are classed together as indirect (paroksha) knowledge, mediated by the senses or by language.
The remaining three are direct (pratyaksha), arising without the mediation of the senses. Avadhi jnana is a limited clairvoyant knowledge of physical objects across distance and time, attainable by some celestial and infernal beings by nature and by ascetics through spiritual discipline. Manahparyaya jnana, mind-reading knowledge, is a still rarer direct perception of the thoughts of other minds, attained only by advanced human ascetics of great purity. Kevala jnana, isolated or absolute knowledge, is the last member, distinguished from the previous two not merely by degree but by kind: where avadhi and manahparyaya are partial and bounded, kevala jnana is unbounded and complete, knowing all substances in all their modes at once, and once attained it does not fluctuate or coexist with any of the four lesser kinds, which fall away when it arises.