Adult dating or no-strings-attached dating is a variant of a traditional online dating service. Where traditional services aim to bringing people together for the purposes of a meaningful relationship or friendship, adult dating  is aimed at those who are seeking short-term sexual encounters. Many adult dating sites focus on the local aspect of finding a match.
Casual dating or a casual relationship is a physical and emotional relationship between two people who may have casual sex or a near-sexual relationship without necessarily demanding or expecting the extra commitments of a more formal romantic relationship.
Dating is a stage of sexual selection in humans whereby two people meet socially, possibly as friends or possibly with the aim of each assessing the other's suitability as a partner in an intimate relationship or marriage.