In geology and geotechnics, a core is a sample of rock, sediment or other geological material obtained using a core, which is commonly a drill hole. There are several parameters and elements that can be studied in a witness, for example; porosity, permeability, mineral composition, microfossils and interstitial water").[1]​ Cores facilitate the direct study of geological materials at distances of hundreds of meters from the Earth's surface.[2]​.

Cores are generally obtained in mining prospecting and exploration campaigns), either on land or on the seabed.[1] In mining, cores are commonly used with drill bits impregnated with small diamond crystals.[3] The process of documenting a core is called logging and is one of the most common work activities related to geology in mining.[2] In large mines, thousands of individual cores have been removed, totaling distances in the millions. of kilometers.[4]​ Witness logging is usually carried out with standardized forms and is often done directly digitally in order to quickly integrate the information with other software.[4]​.