Romantic dating is the process where two people think they might have a spark of attraction, so they spend time with one another in a context that lets them figure out if they’re attracted to each other and they’re compatible for a romantic relationship.
Dating usually precedes a relationship. One of the people expressed interest in the other. If the interest is reciprocated, they start spending time together, usually (but not always) by themselves. They may talk or engage in recreational activities together to gauge how well they get along, and/or kiss, snog, or have sex, to gauge the level of sexual chemistry and compatibility.
Since dating precedes a relationship, there usually isn’t an expectation of monogamy or fidelity, though there may be. Depending on the religious or social attitudes of the folks involved, sex might be part of a date, part of a date after a certain amount of time has passed, or off the table entirely during dating. Dating may also include introducing one’s dating partner to friends or family.
That’s what a sociologist might say, anyway. The less clinical description is dating works when you meet someone you fancy, that person is available for a relationship, so you hang out and have fun while you work out whether you want to be in a relationship with each other or not.