The Coital Alignment Technique (CAT) is a variation of the missionary position that's designed to stimulate the clitoris, making it much easier for the receiving partner to climax during intercourse. Research has shown that only 18% of women are able to climax from penetration alone; for 36.6%, clitoral stimulation is a requirement for orgasm. Positions like the coital alignment technique are a way for partners to enjoy penetrative sex while increasing the odds of orgasm for the receiving partner.
As a variation of missionary position, getting into the coital alignment position is simple; the penetrating partner simply needs to slide forward along their partner's body until the penis (or strap-on) is pointing up, rather than down. This better aligns both partners' pubic bones and allows for stimulation of the clitoris during the penetrating partner's up and down stroke. The receiving partner can also wrap their legs around their partner to open up the clitoris to additional friction and stimulation.