What is a "reference"? What are the issues to be aware of and use of "references"?

A reference is an alias for a target variable, and the action applied is exactly the same as a direct action on a variable. When declaring a reference, remember to initialize it. When the reference declaration is complete, the target variable name is equal to two names, that is, the target name and reference name, and the reference name cannot be used as an alias for the other variable names . Declaring a reference is not a new definition of a variable, it simply means that the reference name is an alias of the target variable name, it is not a data type in itself, so the reference itself does not account for the storage unit, and the system does not assign a storage unit to the reference . You cannot create a reference to an array.

What is a "reference"? What are the issues to be aware of and use of "references"?