Web hosting is a renting space on a web server and is a computer set up with unique software. The web server allows the system to receive requests from the internet for the files it has stored on it and to send those files out, for the system to display them, effectively.
UNIX is the operating system that is running on the server and is the software that makes the system function and manage all the other hardware and software installed on it. There are many variants of UNIX and most of the web servers of today are running on one of UNIX operating systems.
Originally, UNIX operating system was developed by universities for servers and networking. Additionally, UNIX operating system is open for programmers to customize and make improvements and hence, it is an open source protocol and many different versions have arisen due to this facility. LINUX and BSD are the most popular forms of UNIX.
The website is a collection of files being offered on the internet for viewing and so, they need memory space to store and retrieve the information. UNIX has a finite amount of hard disk memory for offering to hosting customers and the space is offered in different package levels. So, by paying more, the customer can get more space to store pictures, web pages, videos and other files. When the website gets bigger than the memory space, the customer has to buy more disk space from the web host.