Originally, it meant "to seduce" or "to have sexual intercourse with".
The Continental experience at that time is amusingly illustrated by a letter that Sigmund Freud wrote to Sándor Ferenczi in 1931 playfully admonishing him to stop kissing his patients, in which Freud warned lest "a number of independent thinkers in matters of technique will say to themselves: Why stop at a kiss?
From the standpoint of anthropology and sociology, dating is linked with other institutions such as marriage and the family which have also been changing rapidly and which have been subject to many forces, including advances in technology and medicine.
As humans have evolved from hunter-gatherers into civilized societies and more recently into modern societies, there have been substantial changes in the relationship between men and women, with perhaps one of a few remaining biological constants being that both adult women and men must have sexual intercourse for human procreation to happen.
It can be a form of courtship consisting of social activities done by the couple.