What is the difference between pass by value and pass by reference?

What is the difference between pass by value and pass by reference?

Pass by value means a copy of the variable is passed, while pass by reference means a reference to the original variable is passed.

Can you give me an example of each?

Sure! In pass by value, if you change the value of the parameter inside a function, it doesn't affect the original variable. In pass by reference, changes to the parameter will affect the original variable.

Which one is more efficient?

Pass by reference is generally more efficient for large data structures since it avoids copying the entire structure.

Are there any languages that use only one of these methods?

Yes, for example, Java uses pass by value for primitive types and pass by reference for objects, while C++ allows both.