"OS"

An "OS" is usually a custom graphical shell for ComputerCraft with poor capabilities. An example of such a program could be any NDFJay copy (or even the original NDF-OS itself). "OS"es are known to flood the ComputerCraft forums with low quality content, and were the reason for the OS forum section to be created.

Specifications
"OS"es usually have common (mis)features:
 * No multitasking
 * Limited number of programs without option to install more
 * Poor to no documentation
 * Pastebin hosted (sometimes MediaFire or Dropbox)
 * No high tech libraries (no hashing, buffering, security, runtime, etc.)
 * Messy, uncommented code with poor indentation that clearly shows it was coded by a newbie
 * Very frequently a NDFJay copy
 * Consists of taskbar at the top of the screen without tasks, sometimes with clock at the top right corner
 * Has a "[Begin]" button linking to all the available functionality
 * Background image
 * The project is said to be in a very early phase of development, which is arguably false since it usually ceases to exist soon after initial release, usually thanks to negative feedback
 * Many bugs, developer is either unwilling to fix them or is not skilled enough to do so
 * Fake loading screens
 * Use of Comic Sans in the forum post
 * Author's first post / first CC/Lua project

Examples
Here are some example "OS"es, AKA how not to do it:
 * LiveOS
 * LimeFyre
 * ToadOS
 * MyOS
 * OS 8
 * And literally dozens of others..