A key element in every relationship is compatibility between the two parties. Beginning from the dating process — and then following in marriage — issues of compatibility can make or break relationships. The word “compatible” gets thrown around a lot in discussions about whether relationships should continue or end. But how do we define compatibility? How many types of compatibility are there? Are all types necessary to sustain a relationship? Here are four primary types of compatibility, and all of them are necessary for healthy love. However, the first three are subject to change, while the fourth type of compatibility is the one that truly cements relationships for the long haul — it is the eternal element that keeps couples together when their looks and interests change. Physical Compatibility Though it may sound superficial, physical compatibility — physical attraction to one another — is necessary for a relationship to take hold and be maintained. You need to be attracted to your partner, and certainly not be repulsed. Beauty is in the eyes of the beholder, and physical compatibility is clearly based on a subjective set of preferences. Nevertheless it is an important component in a relationship. Emotional Compatibility You can be attracted to someone physically, but if emotionally there is no connection, the relationship cannot endure. This happens very often: People look beautiful on paper or in real life, but when you meet and talk to them, you don’t feel anything — there is no “click”. Every healthy relationship needs a feeling of trust and commonality, as well as emotional nurturing. Intellectual Compatibility Intellectual compatibility is two people who respect each other’s intelligence. They share and are stimulated by each others ideas and/or shared intellectual interests. They value each other’s opinion and thoughts. They find each other’s conversation interesting.