Glycemic Index (GI) is a ranking system that measures how quickly carbohydrate-containing foods raise blood sugar levels. Foods are scored on a scale from 0 to 100, with pure glucose having a GI of 100. Low-GI foods, such as whole grains and legumes, are digested slowly, leading to gradual increases in blood sugar, while high-GI foods, like white bread and sugary snacks, cause rapid spikes. Understanding GI can help individuals make healthier food choices, especially for those managing conditions like diabetes. By opting for low-GI foods, people can maintain more stable energy levels and improve overall health.