The AIB model is a simple but powerful tool for understanding how sexual orientation manifests itself in real life. AIB refers to three elements that make up our sexuality: Attraction, Identity, and Behavior.
Attraction refers to a person's capacity for sexual and/or romantic feelings. It is the single most important factor in determining an individual’s sexual orientation. Whether we are gay, straight, or bi is determined fundamentally by our attraction patterns — regardless of whether we act upon them in any way. Attraction generally appears to be involuntary and is shaped by factors such as genes and hormones before birth.
Identity refers to the way a person thinks about themselves and how they want to be seen by others. When someone chooses to make it clear to others what their sexual orientation is, we sometimes call it "coming out". When a person’s identity does not match their attraction patterns (aka sexual orientation), we sometimes say they are "in the closet".
Behavior refers to how a person interacts with others romantically or sexually. It’s important to note that behavior does not necessarily reflect attraction and identity. People who are in the closet might engage in behavior in order to fit in. Bi people may only date one sex because of a preference for monogamy, etc.
Public ideas about sexual orientation are often reduced to one or two of these elements, but it is important to consider all of them. There are many ways that these three components may not be in alignment, and only by looking at all of them can we get a more complete picture of our sexuality.