Abstract: The present disclosure relates generally to data extraction of complex documents and, more particularly, to systems, processes and computer program products configured to automatically extract unstructured data from complex documents and perform table understanding on the extracted data. For example, the method includes: detecting, by the computer system, one or more tables within a digitized document; classifying, by the computer system, the one or more detected tables into at least a first table type; identifying, by the computer system, headers within the first table type; extracting, by the computer system, data within the headers and body cells of the first table type; and mapping, by the computer system, a relationship between the extracted data within the headers and the body cells.