What is the difference between "ByVal" and "ByRef" in VB.NET?

In VB.NET, "ByVal" and "ByRef" are used to pass arguments to a procedure or function.

ByVal: When a parameter is passed by value in VB.NET using ByVal, a copy of the parameter is passed to the procedure or function. Any changes made to the parameter within the procedure or function do not affect the original variable outside of it.

ByRef: When a parameter is passed by reference in VB.NET using ByRef, a reference to the original variable is passed to the procedure or function. Any changes made to the parameter within the procedure or function will affect the original variable outside of it.

It is important to choose between ByVal and ByRef based on whether you want the original variable to be affected by changes made within the procedure or function.