Introduction: Alopecia areata (AA) is a chronic disorder in which the immune system affects the hair follicles, nails, and occasionally, the retinal pigment epithelium. The characteristic manifestation of alopecia areata encompasses isolated, smooth, non-scarring surfaces of hair loss on the scalp or anywhere with hair growth. Objective: to detail the current information related to alopecia areata, etiology, epidemiology, pathophysiology, histopathology, manifestations, diagnosis, treatment and complications of the condition. Methodology: a total of 48 articles were analyzed in this review, including review and original articles, as well as clinical cases, of which 32 bibliographies were used because the other articles were not relevant for this study. The sources of information were PubMed, Google Scholar and Cochrane; the terms used to search for information in Spanish, Portuguese and English were: alopecia areata, hair loss, hair follicles, hair loss, Janus kinase. Results: The lifetime risk of presenting alopecia areata is approximately 2%, it is the second most frequent non-scarring alopecia, after male and female pattern alopecia. So far no study has shown whether the prevalence of alopecia areata is different between ethnic groups. The first appearance of this alteration is more common between the third and fourth decades of life, however it can occur in any age group. Recent evidence suggests that the origin of the condition is autoimmune, with a significant genetic contribution. This alteration is related to medical and psychiatric comorbidities such as depression, anxiety and different autoimmune disorders. Conclusions: Alopecia areata is an autoimmune condition that generates a sudden and uneven hair loss, affecting any area of the body. Recently, alopecia areata has been interpreted as an autoimmune disease with a genetic substrate. The hair follicles do not suffer permanent damage, which is positive because of the possibility of regrowth. It is of vital importance to know the etiology, epidemiology, pathophysiology, histopathology, manifestations, diagnosis and treatment of the condition. At the moment there is no cure for alopecia areata, however the use of some medications has contributed to the improvement of the symptomatology, there are multiple treatment options available. More studies are needed to treat this condition more adequately.