A constant variable is a type of variable whose value cannot be changed once it has been assigned. In programming, this means that after a constant variable is initialized, any attempt to modify its value will result in an error or exception, depending on the programming language used.
For example, in languages like Java or C++, you can declare a constant variable using the keyword ‘final’ or ‘const’. This provides a way to protect values that should remain unchanged throughout the execution of a program, such as mathematical constants like Pi or configuration values.
The use of constant variables improves code readability and maintainability, as it signifies that the value is intended to remain fixed. It also helps prevent accidental changes that could lead to bugs or unintended behaviors in your application.