Quantitative Trait Loci (QTL) are specific regions of DNA that are associated with particular traits or characteristics in organisms. These traits can be measurable, such as height, weight, or yield in plants. By identifying QTL, researchers can understand the genetic basis of these traits and how they are inherited. QTL mapping is a technique used to locate these regions on chromosomes. It involves analyzing the genetic variation in a population and correlating it with the observed traits. This information is valuable in fields like agriculture, where it can help in breeding programs to enhance desirable traits in crops and livestock.