Telomeres are repetitive DNA sequences at the ends of chromosomes that protect genetic data during cell division. Think of them like the plastic tips on shoelaces—they prevent the chromosome from fraying.

Each time a cell divides, telomeres shorten slightly. When they become critically short, cells enter senescence (aging) or die. This process is a fundamental mechanism of biological aging.

Telomere length is now considered one of the most accurate biomarkers of biological age—and it can be measured through simple blood tests.