Kinship can refer both to the study of the patterns of social relationships in one or more human cultures, or it can refer to the patterns of social relationships themselves. Over its history, anthropology has developed a number of related concepts and terms, such as "descent", "descent groups", "lineages", "affines", "cognates", and even "fictive kinship". Broadly, kinship patterns may be considered to include people related both by descent (one's social relations during development), and also relatives by marriage.