While installing Ubuntu, It asked me to allocate something called Swap Space, What exactly is it? What would happen if i dont allocate it?/ What is the use if i did allocate?
Swap space is space on the disk used as if it was temporary memory (RAM). If you did allocate it, your computer would use it when its RAM is starting to be used up. If you don't allocate it, nothing happens unless you run out of RAM space. Then any program wanting more RAM would be closed.
If you want to use hibernate, you need at least as much swap as you have RAM. This is because when your computer hibernates, it copies the RAM to the swap and turns off.
As binW says, swap is slower than RAM.
It is a virtual memory space which is used for hibernation, intensive memory processes and general memory consuming applications. To see details of your swap partition just run at the terminal:
Swap is used by the kernel of your system whenever it really needs it. Swappiness is a term which refers to the tendency of the kernel to move processes out of physical memory (hardware RAM) to the swap disk. To change the default tendency of your system run at the terminal:
gksudo gedit /etc/sysctl.conf
and change the variable:
If you hibernate then as far as I know you'll need swap to do so.