Bisexual (often shortened to bi) refers to someone who is attracted to people of two or more genders. These two genders are most commonly assumed to be men and women, but they do not necessarily have to be. Bisexual people do not have to be attracted to both genders equally. For example a bisexual person may be attracted to women 80% of the time and men 20% of the time.
According to Alfred Kinsey's research in the mid-20th century, most humans are not exclusively heterosexual or homosexual. The Kinsey scale measures sexual attraction and behavior on a seven-point scale ranging from 0 ("exclusively heterosexual") to 6 ("exclusively homosexual"). It was found that most people fall somewhere in the 1-5 category.
The bisexual consists of a pink stripe on the top, representing homosexuality, and blue stripe on the bottom, representing heterosexuality, and a purple stripe in the middle representing bisexuality.
The Greek prefix bi- mean 'two'.