Final answer:
ByRef and ByVal are terms used in programming to indicate if a function receives a reference or a copy of a variable. ByRef allows the function to modify the original variable, while ByVal protects the original variable from being modified by creating a copy.
Step-by-step explanation:
The terms ByRef and ByVal pertain to how arguments are passed to functions or procedures in programming languages. When a parameter is passed ByRef (by reference), it means the function can modify the original variable's value that is passed in. This can be useful when you want the function to directly alter the state of the object or variable you're passing. In contrast, when a parameter is passed ByVal (by value), the function receives a copy of the value, so the original variable's value that is outside the function is not affected by any changes made within the function. This is generally the default in many programming languages, as it promotes functional purity and prevents unintended modifications.
In summary, the choice between ByRef and ByVal should be based on whether you need the function to alter the calling variable's value directly (ByRef) or if you want to protect the original value from changes (ByVal).