Fossils are the preserved remains, impressions, or traces of any once-living thing from a past geological age. They include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood, and more. Fossils can be categorized into two main types: body fossils and trace fossils. Body fossils represent all or part of the organism, such as bones, shells, and leaves, while trace fossils are the preserved evidence of an animals activity or behavior, such as tracks, trails, burrows, and waste products. Fossils can also be categorized into five categories based on finer aspects: body fossils, molecular fossils, trace fossils, carbon fossils, and true form fossils.

Fossils are useful in the exploration for minerals and mineral fuels, as they serve to indicate the stratigraphic position of coal seams and can be used to study the subsurface stratigraphy of oil and natural gas deposits. They also provide important evidence for evolution and the adaptation of plants and animals to their environments, and can be used to determine the relative age of different layers of rock or strata. Fossils give us a useful insight into the history of life on Earth, showing us where life and humans came from, how the Earth and our environment have changed through geological time, and how continents, now widely separated, were once connected.

Fossil collecting is the collection of fossils for scientific study, hobby, or profit. Fossil collection as performed by paleontologists, geologists, and other scientists typically involves a rigorous excavation and documentation process, while fossils collected by hobbyists and commercial entities are often not carefully documented or excavated, resulting in a loss of data from the site and risking potential damage to the specimen.