Linus Torvalds wrote the first Linux kernel in 1991 and made its source code freely available on the internet. Linux kernel is coded in C programming language. Linux gained its popularity because it has always been distributed as free software. Since the source code is readily available, users can freely tweak the kernel to suit their specific needs. Linux is a complete multitasking, multiuser operating system. This means that many users can log into and run programs on the same machine simultaneously.
About device drivers:
Device driver is software which gives a device its behaviour. Device driver is a piece of software which gives intelligence to hardware to make work as it should. A device driver, often called a driver for short, is a computer program that enables the OS (Operating system) to interact with a hardware device. Driver software essentially contains a set of instructions that provides the operating system with the information on how to control and communicate with a particular piece of hardware.
Device drivers serve several different purposes. In their purest form, they are the link between software and hardware. For example, applications generally do not care where on a storage device a file resides; instead, they submit general calls to the operating system to open, close, modify etc. to a file. It is the task of the operating system and the device drivers to co-operatively locate the file on the storage and read from or write to the correct physical location within the storage hardware.