What term refers to a value that cannot be altered by the program during execution?

The term that refers to a value that cannot be altered by the program during execution is a constant. Constants are fixed values that, once assigned, remain unchanged throughout the program's runtime. This immutability is crucial for certain applications, such as maintaining consistent values like mathematical constants (e.g., Pi) or configuration settings that should not fluctuate during execution.

Using constants allows developers to write more secure and predictable code, as they prevent accidental modification of critical values. In contrast, variables are designed to hold reusable values that can be changed at any point in the program, which serves a different purpose. Functions are blocks of code designed to perform specific tasks and can use both constants and variables. Parameters are values passed into functions to customize their behavior but do not define immutability in the same way that constants do.