Think of the Internet as a giant book library which is full of many books. But, each book is unique with a unique registration number or id. The same goes for the websites that are analogous to books and the Internet to the giant library respectively. Now to find a particular site you need to enter the designated unique name that is called a domain name.
A domain name is like an address to your website that helps users to reach it easily.
A domain name can be anything ranging from a collection of numbers, characters or letters with domain extensions such as .net, .com, .in or more. A domain needs to be registered first before it goes into existence.
A typical domain name goes like:
www.domainnameofyourchoice.com/net/in/org/info