 The Delta variant of COVID-19, also known as B.1.617.2, is rapidly increasing infections worldwide due to its high transmissibility. This variant is 60% more contagious than the Alpha variant and has become the dominant strain as of August 2021. Despite vaccination efforts, COVID-19 has resurfaced in infections in countries like the U.S. The Delta variant is more deadly due to its ability to cause severe respiratory illness and hospitalization. Vaccine companies such as AstraZeneca, Pfizer slash BioNTech, and Moderna have reported that their vaccines can provide protection against this variant with slightly reduced efficacy. This review article provides a comprehensive summary of the Delta B.1.617.2 variant and its transmissibility factors. This article was authored by Cheyenne Shizadigan, Nazanine Alligmand, Michael Fox, and others.