Floating drug delivery systems are among the most extensively studied strategies for prolonging the gastric residence of orally administered formulations. Their value rests on a simple physical premise: a dosage form whose bulk density remains lower than that of gastric fluid will stay buoyant on the stomach contents, releasing drug at a controlled rate within the gastric milieu and the upper small intestine, where the absorption windows for many therapeutic agents are concentrated. The present review examines the rationale, classification, and design principles of floating gastroretentive systems, with attention to both effervescent and non-effervescent formulations. Polymers commonly used in floating systems, including hypromellose grades, sodium alginate, Carbopol, polyethylene oxide and Eudragit polymers, are discussed alongside gas-generating agents and low-density excipients. Manufacturing methods covered include direct compression, wet granulation, solvent evaporation for hollow microspheres, and ionotropic gelation for floating beads. Standard in vitro evaluations such as floating lag time, buoyancy duration, swelling, and dissolution under simulated gastric conditions, together with in vivo techniques such as gamma scintigraphy, are reviewed. Marketed products with established clinical use are tabulated. Recent advances covered include three-dimensional printing of personalised floating dosage forms, floating in situ gels, raft- forming nanocomposite systems, and the application of artificial neural networks to formulation screening.