if I upgrade to Unity 5 will I lose my current project?

I want to download Unity 5 but I’m afraid that I will lose all my work. I was thinking about backing up my current project and if it didnt transfer to unity 5, then I can just open it back up in 4.whatever it is I’m using. However, there are literally no tutorials on how to backup a project. Everyone just says copy the folder, but others say that doesn’t work. I don’t even know which folder they are referring to specifically. I assume it’s the one with my projects name on it. Rather than risk it though I’d rather just continue using old Unity, so I’m asking those of you that have upgraded if your projects still work

Always make a backup!

Never use that backup, only use copies of it.

Just Zip or Rar the entire folder. Seems to work for most.

Back up your project if something goes wrong,
It should ask you to upgrade your project (by clicking go ahead button) when opening your project for the first time