"As we all know, the operating system is an essential part of any computer system, but what most of us don't understand are the intricacies of how OS environments operate. This article discusses the ways of extending the operating system by various ways including, but not limited to, recompiling the kernel and managing libraries. Extensibility is the need of time. It gives the user more 'power' over the machine, since every user can have his 'personalized' copy of the OS. This approach of extending the operating system at user level is more advantageous than other methods."