It can be a form of courtship consisting of social activities done by the couple.
Communities exerted pressure on people to form pair-bonds in places such as Europe; in China, society "demanded people get married before having a sexual relationship" and many societies found that some formally recognized bond between a man and a woman was the best way of rearing and educating children as well as helping to avoid conflicts and misunderstandings regarding competition for mates.
A few centuries ago, dating was sometimes described as a "courtship ritual where young women entertained gentleman callers, usually in the home, under the watchful eye of a chaperone," but increasingly, in many Western countries, it became a self-initiated activity with two young people going out as a couple in public together.
Still, dating varies considerably by nation, custom, religious upbringing, technology, and social class, and important exceptions with regards to individual freedoms remain as many countries today still practice arranged marriages, request dowries, and forbid same-sex pairings.
It generally happened in that portion of a person's life before the age of marriage, enabled dates to be arranged without face-to-face contact.
Cars extended the range of dating as well as enabled back-seat sexual exploration.
These species-particular behavior patterns provide a context for aspects of human reproduction, including dating.