The GNU/Linux Operating system does not use a single folder as a dump ground Here is a list of various directories and their contents...
/boot : the linux kernel and boot loader configuration files
/usr : Program files
/etc : Configuration files
/var : Mail, print web spool files
/tmp : temp directory
/home : Home directories of various users
/dev : Device files corresponding to various peripherals of your comp. (hard disk, printer, mouse, modem)
/mnt : Devices mounted onto OS to increase storage space
/lost+found : Orphan files are moved here
/root : Root's home directory
/proc : Process information pseudo filesystem.
/bin : various console utilities and apps
/sbin : system administration utilities
/lib : Shared Library files for your operating system.
Apart from these, you also have a swap partition that stores data swapped by the linux kernel.
As you can see, /etc is roughly equivalent to your windows registry. /usr can be called as Program Files directory... /boot & /lib can be called as \Windows\System32 directory. Contents of /mnt can be thought of as various drives in windows.