Patrilineality (or agnatic kinship) is a system in which one belongs to one's father's lineage. It generally involves the inheritance of property, names or titles through the male line as well.

A patriline is literally a father line; one's patriline is one's father and his father and his father... and so on. The two corresponding adjective forms are patrilineal and father-line. One's patriline is thus a line of descent from a male ancestor to a descendant (of either sex) in which the individuals in all intervening generations are fathers. A man's genetic Y-DNA and his family name (in most cultures) have descended down this same line from father to son. In a patrilineal descent system (= agnatic descent), an individual is considered to belong to the same descent group as his or her father. This patrilineal descent pattern is much more common than matrilineal descent, see the article on family names which are almost all patrilineal surnames. Also for an indepth treatment of current patrilineal surnames, globally, see the same article.