What keyword is used to declare a constant in a program?

The keyword used to declare a constant in a program is "const." When you use "const," you are indicating that the value assigned to the variable cannot be changed throughout the runtime of the program. This is particularly useful in programming to create variables that are meant to represent fixed values, such as mathematical constants or configuration settings, where altering the value could lead to unintended consequences or bugs in the code.

In many programming languages, using "const" enforces type safety and can help prevent accidental modifications of values that should remain constant. For instance, in languages like C++ and Java, using "const" signals to both the compiler and other programmers that the value will not be altered after its initial assignment, enhancing code readability and maintainability.

The other keywords in the options serve different purposes: "define" is commonly associated with preprocessor directives in C/C++, "static" is used mainly to define the lifetime and visibility of a variable, and "final" is primarily used in Java to declare constant variables or to prevent overrides in classes and methods, but it does not universally apply across all programming languages like "const" does.