Telomerase is an enzyme that plays a crucial role in cellular aging and regeneration. It is responsible for maintaining the length of telomeres, which are protective caps at the ends of chromosomes that shorten as cells divide. Telomerase helps to counteract this shortening by adding nucleotides to the end of the chromosome, effectively extending its lifespan and allowing it to continue dividing. This enzyme is present in most human cells but its activity decreases with age, which contributes to cellular aging and the development of various diseases.