Sanitary pads (napkins) are absorbent, disposable menstrual hygiene products with a topsheet (breathable cotton/nonwoven), superabsorbent polymer core (SAP locks 100-500ml fluid), and waterproof backsheet; wings and adhesive secure to underwear. Types: regular/maxi (medium flow, 20-50ml, 240mm), super/heavy (XL 320mm+ wings for heavy flow), overnight (350-420mm extended back for night), panty liners (light spotting), ultra-thin (discreet moderate), organic cotton (chemical-free sensitive skin). Change every 4-8hrs to prevent TSS; biodegradable bamboo variants reduce plastic waste.