Files Uploaded from UI where do they reside.... in Heap or in RAM Memory

Hi All,

I wanted to check few things like,

I have a file Upload component where i can upload the file.... Once the file is Uploaded into the screen, where does this actually reside as per the memory, 

1.When i click on Upload it takes time to load on to the screen to tell me the size--- till that time where is the file loaded.

2.Once the file is uploaded on screen where is the file loaded-is it in Heap or Memory.

3. Once you click on submit where does it goes.- is it Heap or Is it Memory or is it Disk