The core component of the operating system. The kernel schedules activities (threads) for the computer processor to perform, and it handles interrupts and exceptions. If the computer has multiple processors, the kernel synchronizes activity among the processors to optimize performance.
A field or expression used to identify a record; often used as the index field for a database table.
Or reserved word. A word that has special meaning to a program or in a programming language. Reserved words usually include those used for control statements, data declarations, and the like. A reserved word can be used only in certain predefined circumstances; it cannot be used in naming functions, variables, structures, labels, classes, or user-generated tools such as macros.