Linux folder hierarchy

I am too lazy to write my own stuff because other posts on the internet explain this so well. Original post: http://www.techrepublic.com/article/learn-the-hierarchy-within-the-linux-directory/5031957

/bin
The /bin directory is where many of the basic Linux commands are housed. The /bin directory is in all standard user $PATHS, meaning that any executable contained within /bin can be executed from anywhere in the directory structure. The globalization of the /bin directory allows the user to run the ls (and other commands) on current working directories and files.

/boot
The /boot directory houses all the boot code for the Linux system. Crucial files are housed within this directory and, unless a kernel recompilation is necessary, it is best not to touch the contents of /boot.

/dev
The /dev directory seems to be the biggest mystery to new Linux users. To understand this directory, you need to keep in mind that everything is treated as a file in Linux—even devices such as printers, scanners, and hard drives.

Since everything is a file in Linux, every file needs a centralized location to be housed, and what better place to house device files than the /dev directory?

By running the ls command from within the /dev directory, you will see entries such as audio,cdrom, hda, sda, and ttyS0. Each of these entries represents a possible hardware (or system) device for the machine. For example, on my machine, I know that /dev/hda is the first primary partition on my hard drive.

/etc
The /etc directory is a vital part of the Linux system because it contains the majority of the necessary configuration files and resources. Most of these files are saved in text format, so they are editable with any text editor. The permissions of the /etc directory dictate that only the root user can modify the contents. Do not change this permission.

/home
The /home directory houses all the individual user account information as well as the users' personal files. If a particular Linux system has normal user accounts such as Jack, John, and Jim, then /home will contain directories for each user (named after each respective user).

/lib
The /lib directory contains all the shared library files necessary to run the Linux system. These files are all dynamically linked from various places around the hierarchy.

/lost+found
The /lost+found directory contains stray files that have been picked up after a system crash. Typically, after a crash, lost files will appear as numbered files (not as the original filenames).

/opt
The /opt directory is simply a location where larger packages (such as StarOffice, OpenOffice, and Applixware) should be installed.

/proc
The /proc directory contains virtual files for various processes on a machine such as the CPU, RAM, I/O Ports, and Interrupts.

/sbin
The /sbin directory contains many applications that are reserved for the root user. The /sbindirectory should house any applications that are necessary to start system processes, as well as many of the configuration utilities (such as netconf).

/tmp
The /tmp directory holds the temporary files that are needed for various applications and processes.

/usr
The /usr directory contains a number of very important subdirectories such as:

/usr/bin
This directory is like /bin, only it contains more advanced commands and many user-installed commands.
/usr/src
This is where the kernel source is located.
/usr/local
This directory is commonly used to install packages from source.
/usr/sbin
This directory contains system commands that can be executed only by the system or the root user.
/usr/doc
This directory contains the documentation installed on the system.
/usr/man
This directory contains the files used by the man help system.
/var
The /var directory contains system files, such as logs, and often-changing user/system files, such as print spoolers and mail spoolers.