# References: Two Names, One Object

Why copying a variable that holds an object copies only the note that says where it is, so two names can change one object; how to make a real copy; and null, None and undefined, the note that points at nothing.

![Cheat sheet: References: Two Names, One Object](https://fsdtrainingmedia.blob.core.windows.net/public/images/2026/11/fedefcc14f514056acda156a0b7c5a12.webp)

- Category: Data Structures
- Level: Apprentice
- Tags: c-sharp, java, JavaScript, Null (software-development), Object (oop), python, Reference (software-development), typescript
- Updated: November 3, 2026

Source: https://www.ask-codey.com/cheat-sheets/ds-code-you-need-references-cheat-sheet