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 while staying loyal to each other without necessarily demanding or expecting the additional commitments of a more formal romantic relationship. Motives for casual relationships vary. There are significant gender and cultural differences in acceptance of and breadth of casual relationships, as well as in regrets about action/inaction in those relationships.

Casual dating may or may not entail partner-exclusivity. In each case, the relationship's dominance in the lives of those involved is being voluntarily limited, and there is usually a sense that the relationship is intended to endure only so long as both parties wish it to. Casual relationships sometimes include mutual support, affection and enjoyment, which underpin other forms of loving relationship.

A casual relationship is sometimes referred to as a "no strings attached" relationship, as a situationship, or as a fling.

A "no strings attached" relationship is most commonly found in young adults such as college students. The shift from childhood to adulthood brings on much exploration in different fields. One of these fields include relationships and sexual activity. Grello et al.'s study suggests that, in most cases, students who lost their virginity in high school did so in a romantic relationship. After experiencing sexual intercourse, many college students go on to have casual sex with either friends or peers they have been recently or newly acquainted with.

A casual relationship, unlike a romantic relationship, is difficult to ascribe norms, scripts, and expectations to. Rebecca Plante, an associate professor at Ithaca College who has specialized in research on casual relationships, says that this type of relationship can be beneficial, saying that casual relationships can establish a "healthy outlet for sexual needs and desires."

J.A. Lee defined two main types of lovers for college aged young adults: "Eros" lovers who are passionate lovers, and "Ludas" or "Ludic" lovers, which are game-playing lovers. "Eros" lovers are lovers that immediately form a close connection. They fall in love with the physical appearance of another before considering other characteristics of the person. This type of lover also commits to casual sex relationships. Because physical appearance is the main reason for their attraction, it is difficult for a genuine romantic relationship to form. "Ludic" lovers look for the feeling of a conquest, and typically enter a relationship or hook-up with very little or no intentions of commitment. In most cases, they will have more than one sexually active partner at a given time. They also find it difficult to consider a serious relationship.

Many casual relationships establish guidelines or a set of rules. The two participants in the relationship will reach an agreement about what each expects from the relationship. Another major concern is that one of the partners will develop romantic feelings for the other. Communication between the two partners is essential to making this type of relationship work and because the partners in the casual relationship are often friends beforehand, talking to one another is a much simpler task.

Casual relationships, being a mix between a friendship and a non-romantic sexual relationship, result in the partners facing many challenges in maintaining a working relationship. Based on the exchange theory, Hughes witnessed an individual dependency on either partner as the exchange of resources, knowledge, rewards, and costs of items, becomes more and more prominent. The partners may become dependent on advice the other partner gives, or the company they receive when being around one another. This may be a one-way street and one partner may not feel this way. Any partner that is not fully dependent upon the other typically controls the casual relationship. The dependent partner is more submissive to their dominant partner as they do not want the relationship to end. This allows the less dependent partner to be able to fix and maintain the relationship the way he/she wants it to be. They normally control when they meet up, when they have sex, and when they do things together.