In many cultures, especially traditional western, a father is usually the husband in a married couple. His role in the family is celebrated on Father's Day.
Many times fathers have a very important role in raising offspring and the title can be given to a non-biological father that fills this role. This is common in step-fathers (male married to biological mother). In most family structures the father is both a biological parent and a primary caregiver.
In East Asian and Western traditional families, fathers are the heads of the families, which means that his duties including providing financial support and making critical decisions, some of which must be obeyed without question by the rest of the family members.
As with cultural concepts of family, the specifics of a father's role vary according to cultural mores. In what some sociologists term the "bourgeois family", which arose out of typical 16th- and 17th-century European households and is often considered the "traditional Western" structure, the father's role has been somewhat limited. In this family model the father acts as the economic support and sometimes disciplinarian of the family, while the mother or other female relative oversees most of the childrearing. This structure is reflected, for example, in societies which legislate "maternity leave" but do not have a corresponding "paternity leave."
However, this limited role has increasingly been called into question. Both feminist and masculist authors have decried such predetermined roles as unjust. A nascent fathers' rights movement seeks to increase the legal standing of fathers in everything from child-custody cases to the institution of paid paternity or "family" leave.
Dad, daddy, pop, papa, and pa are some common or familiar words for a father. Many times these terms denote affection or a paternal role in a child's life. The father may only be the biological parent: "Anyone can be a father, but it takes someome special to be a Dad." As such, someone can be a father and not a dad, or a dad and not a father.
In the case of a stepfather when a child calls them dad this often indicates the child has finally accepted them in the loving parental role.
For some animals, it is the father who take care of the young.
Human
Other Animals