As you already know, in Windows just after the install there are a few standard directories like: Windows, Program Files, Documents and Settings/Users. In Linux a similar structure exists but with much more directories. I will present you below the most important ones:
/home = contains user’s personal folders and files
/root = contains the files and folders of root user
/dev = special files for system hardware devices
/etc = system configuration files for operating system and applications
/tmp = here are stored the temporary files
/opt = additional installed software which is not part of the operating system – 3rd party software
/boot = contains a minimum number of files needed by the operating system to boot – a part of bootloader, bootmanager and the kernel
/proc = contains a pseudo file system which does not exists on the harddisk, all the resources under /proc are information that the kernel presents to the user as files, this way the user can access information about hardware, processes, settings and so on. Some of the files can be modified and the effect is replicated directly into the Kernel
/var = contains variable data/data that changes very often
/var/mail = contains the mailboxes if a webserver is installed
/var/log = log files created by the system or other applications
/bin = files that can be executed (binary files) used to troubleshot or debug the operating system.
/sbin = binary files that are used for system administration (can be used by root user)
/lib = libraries of data used by the kernel and Linux OS (Operating System), needed to boot and to run commands from /bin and /sbin
/mnt = used to temporary mount other file systems
/usr = the place where user’s applications are installed. This folder also contains a file structure.
/usr/bin = commands available for the user
/usr/lib = libraries available for the user
/usr/local = used to install available software only on the local machine
/usr/share = architecture independent data that is not modifying
