This definition comes from Wikipedia.
"Archaeology (sometimes written archæology) or archeology (from Greek ἀρχαιολογία, archaiologia – ἀρχαῖος, arkhaīos, "ancient"; and -λογία, -logiā, "-logy") is the science and humanitythat studies historical human cultures through the recovery, documentation, analysis, and interpretation of material culture and environmental data, including architecture, artifacts, biofacts, and landscapes. Archaeology aims to understand humankind through these humanistic endeavors. In the United States the field is commonly considered to be a subset of anthropology, along with physical anthropology, cultural anthropology, and linguistic anthropology, whilst in British and European universities, archaeology is considered as a separate discipline.
Archaeology involves surveyance, excavation and eventually analysis of data collected in order to learn more about the past. There are various different goals to the discipline, including the documentation and explanation of the origins and development of human cultures, understanding culture history, chronicling cultural evolution, and studying human behavior and ecology, for both prehistoric and historic societies.Indeed, archaeology is particularly useful in discovering information about human Prehistory, which comprises over 99% of total human history, due to the lack of written sources for this period and the full reliance on archaeological evidence. However, alongside this it is also used to investigate more recent history, even that reaching back only a few decades."
It's just that some of us prefer doing our archeological digs in someone's garage.