Gastropod mucus, a complex and versatile substance produced by snails and slugs, plays a critical role in their biology, and holds promise for various applications. This review offers a comprehensive and insightful overview of the current state of knowledge on gastropod mucus, encompassing its composition, biological roles, and potential applications. We delve into the multiple intricate mechanisms by which snails and slugs employ mucus to achieve their various biological goals such as locomotion, defense against predators, protection from environmental threats, communication, mating, homing behavior, nutrient recycling, and regulating population density. The focus then shifts to an examination of the practical applications of gastropod mucus such as antipathogen properties, skincare and antiaging, surgical adhesive and drug delivery, dental and orthopedic application, engineering, and biomimicry, as revealed through various studies. We also critically assess the results and identify areas for further research. This critical review helps to refine our understanding of the true potential of gastropod mucus and guides future investigations. Finally, we discuss the challenges of studying gastropod mucus.