Alopecia areata is an autoimmune condition that causes sudden hair loss in patches. It occurs when the body's immune system mistakenly attacks hair follicles, leading to hair falling out. This condition can affect anyone, regardless of age or gender, and may result in complete baldness in some cases. The exact cause of alopecia areata is not fully understood, but it is believed to involve genetic and environmental factors. While there is no cure, various treatments, such as topical medications and corticosteroids, can help stimulate hair regrowth and manage symptoms.