Variants of SARS-CoV-2 are different strains of the virus that causes COVID-19. These variants arise due to mutations in the virus's genetic material as it replicates. Some variants may spread more easily, evade immunity from previous infections or vaccinations, or cause more severe illness. Notable variants include Alpha, Beta, Gamma, and Delta, each identified by specific mutations. The Omicron variant, first detected in late 2021, has numerous mutations and has led to increased transmission rates globally. Monitoring these variants is crucial for public health responses and vaccine effectiveness.