CRISPR-Cas9 is a Nobel Prize winning groundbreaking technology that allows precise editing of an organism’s genome, including that of humans. This technology can specifically modify target DNA sequences, thereby improving its action. The Cas9 enzyme and guide RNA are vital components of the CRISPR-Cas9 complex. The two main mechanisms responsible for its action are non-homologous end joining (NHEJ) and homology-directed recombination (HDR). There are several strategies that can be employed to deliver the CRISPR components into target cells. These include viral vectors, lipofection, electroporation, microinjection, and using nanoparticles. This robust technology has important applications in medicine and agriculture.