Upgrading unity. Files kept?

This is probably a stupid question for most people, but i have never upgraded unity before so i have no experience in what happens.
The newest version of unity allows IOS and Android development for free! It is like a dream come true for me, cause now I’ll be able to make android and iphone games before i finish school.

Since i have never upgraded I am unsure whether or not old files for unity are kept or lost. Since I am working on a school computer for most of my time programming, and that computer has files on unity belonging to other people, I want to make sure that no files are lost.

Do you lose files when upgrading or are they kept and they stay accessible from the project wizard that comes up at the start?

Regardless of the answer, i will still definitely back up all my files incase. Thanks in advance.

To use the free version of Android and IOS in unity you do not need to upgrade your unity, you need to upgrade the license and this will not affect the files.

See my post here on how to upgrade the license: Unity android and IOS basic - Questions & Answers - Unity Discussions