Most dildos are intended for vaginal or anal penetration and stimulation, whether masturbation or with a sexual partner. Dildos have fetishistic value as well, and may be used in other ways, such as touching one’s own or another’s skin in various places, often during foreplay or as an act of dominance and submission. If of appropriate sizes, they can be used as gags, for oral penetration for a sort of artificial fellatio. Dildos, especially specially designed ones, may be used to stimulate the G-spot area.

A dildo designed to be inserted in the anus and remain in place for a period of time is usually referred to as a butt plug. A dildo intended for repeated anal penetration (thrusting) is typically referred to as an anal dildo or simply “dildo”. Anal dildos and butt plugs generally have a large base to avoid becoming accidentally completely inserted into the rectum, which may require medical attention to remove. There are also double-ended dildos, with different-sized shafts pointing in the same direction, used by women to accomplish vaginal and anal penetration at once, or for two partners to share a single dildo. In this case, the dildo acts as a sort of “see-saw”; each partner takes an end and receives stimulation.

Some dildos are designed to be worn in a harness, sometimes called a strap-on harness or strap-on dildo, or to be worn inside, sometimes with vibrating devices attached externally. Strap-on dildos may be double-ended, in which case they are meant to be worn by users who want to experience vaginal or anal penetration while also penetrating a partner. They may also be used for anal penetration of men. If the penetration is done by a female partner to a male partner, the act is known as pegging.

Other types of dildos include those designed to be fitted to the face of one party, inflatable dildos, and dildos with suction cups attached to the base (sometimes referred to as a wall mount). Other types of harness mounts for dildos (besides strapping to the groin) include thigh mount, face mount, or furniture mounting straps.

Recent social acceptance and popularity has resulted in the emergence of highly adorned dildos. These are often made of expensive materials and may also be jewelled.