Adeno-associated virus (AAV) is a virus commonly found in human population, which exhibits great biodiversity and is not considered a cause of disease. Nowadays, it is often used in gene therapy, as a vector, due to the simplicity of controlling its replication, its long-term expression in cells, and its lack of pathogenicity. One of its main characteristics is the susceptibility to modification of its genome and the ability to package virions, despite removal of a significant portion of the wild-type AAV genes and their replacement with transgenes. Various modifications are used in genome editing to improve the control of transgene expression through adjusting the intensity and specificity of expression. Expression control is often achieved by altering promoters and other regulatory elements. The genome is frequently modified because of the size limitations of the insert. This problem is solved by using smaller versions of functional transgenes and a dual vector strategy. Furthermore, capsid modifications of this vector are a common subject of research as they can lead to specific vector tropism and, consequently, make gene therapy more precise. Capsid protein adjustments are also made to reduce immune response during gene therapy administration, aiming to avoid vector recognition by antibodies and cytotoxic T lymphocytes. Due to these, and some other modifications of the virus, this vector is nowadays often part of gene therapies and forms the basis of therapies that are currently in clinical trials. Generally, the favorable nature of AAV virus and many interventions it undergoes could ensure the supremacy of AAV vectors in the field of viral vectors.