The Linux filesystem in simple words

If you are new to Linux, one of the first things that, probably, dizzied you was that the linux filesystem is nothing like the one you were used in Windows. The first thing a new Linux user should understand is that while in Windows each partition/device is it’s own root (C: D: E:), in Linux every partition/device is mounted under the root directory (“/“) and it is represented as a sub-directory. The second thing the new user should understand is the purpose of each directory contained under the / (root directory). In order to help you familiarize with it, in the next section I gave a description of each part (directory) of the root system. Don’t worry, is not a complicated thing.

/ -root directory of your entire file system.

/bin/-executables needed during bootup, the shells, as well as most used commands (cp, mv, ls etc.) and other essential programs, shared by the system, the system administrator and the users.
/boot/-files used by the boot loader (the application that loads first when the computer is booted and if you have more than one OS on your computer, gives you the option to select one). Also stores the configuration files.
/dev/-device files. In Linux, hardware devices are represented as files with special properties (A file, as well as a hardware, can be read from and written to, isn’t it so?)
/etc/-system configuration file (similar to the data in the Control Panel in Windows)
/home/-personal directories for common users. This directory also contains the user specific settings (for different programs) and the customization files.
/lib/-shared libraries required by system programs (similar -somehow- to Windows DLL files). This directory also contains the kernel modules
/media/-mount point for removable media (usb, sticks, cdrom). Any device/partition mounted in this directory will have a shortcut on the desktop.
/mnt/-mount points for temporarily mounted filesystem (hdd partitions, network shares).
/opt/-optional applications (extra and third party software, add-on packages)
/sbin/-system administration as well as maintenance and hardware configuration programs (not intended for use by general users)
/srv/-data files for particular service provided by this system
/tmp/-temporary files. This directory is cleared out at reboot.
/usr/-multi-user shared binaries and files (utilities, applications, libraries, documentation etc.). Similar, somehow, to Windows Program Files
/var/-variable files (log files, the mail queue, the print spooler area)
/root/-personal (home) directory of the system administrator (root user)
/proc/-virtual file system containing information about system resources (tracks the state of the operating system kernel and the processes running on your computer)
You can find extended information about the Linux File System on the Filesystem Hierarchy Standard webpage.