Anthocyanins are water-soluble flavonoid pigments responsible for red, purple, and blue colors in many fruits, vegetables, and flowers. They consist of anthocyanidin aglycones glycosylated with sugars, existing as flavylium cations at low pH. They exhibit antioxidant, anti-inflammatory, and potential health-promoting properties including cardiovascular benefits and protection against oxidative stress. Stability is pH-dependent, shifting from red (acidic) to blue (neutral/alkaline). Common sources include berries, grapes, and red cabbage. Used as natural food colorants (E163) with GRAS status in the US. They are biosynthesized via the phenylpropanoid pathway and vary in structure based on hydroxylation and methylation patterns on the B-ring.