Caps and closures define how a container is sealed and opened, providing protective containment and a means for access and product dispensing. They ensure product safety and security by preventing leakage, contamination, and loss of volatile substances, while also offering features like tamper evidence and child resistance. The term "closures" is broader, encompassing caps as well as other sealing devices like lids, pumps, and sprayers, all designed to meet specific product and user needs.