The concept of PMEST, which stands for Personality, Matter, Energy, Space, and Time, is known for being developed by S. R. Ranganathan. He was an Indian librarian, mathematician, and philosopher who is widely regarded as the father of library science in India. Ranganathan introduced PMEST as the five fundamental categories in his faceted classification theory, particularly in his Colon Classification system. These categories represent different aspects of a subject to facilitate its systematic classification:
- Personality: the core or focal subject itself
- Matter: the substance or material of the subject
- Energy: the activities or processes related to the subject
- Space: the spatial dimension or location
- Time: the temporal aspect related to the subject
Ranganathan's PMEST framework was a major innovation in knowledge organization and library classification
