Age acceleration refers to a measure of biological aging that is based on changes in DNA methylation levels. By examining patterns of methylation at specific sites on an individual's DNA, researchers can estimate the biological age of that individual, which may differ from their chronological age. Age acceleration has been found to be associated with various health outcomes and can serve as a predictor of disease risk and mortality. This research area aims to better understand the factors that contribute to accelerated aging and its implications for overall health and longevity.