There are lots of possible answers to this question, but i decided to divide it into just three, for personal, business and informative/interactive purposes.

? Personal

- People often create personal websites to let others know about their personal informations, hobbies, interests, beliefs and make friends with others. Personal websites usually composed of pictures,videos, articles and chatbox for interactivity with other people specially with family,friends and loved one.

? Business

- Aside from media,banners and streamers, internet is one of the excellent medium to promote your business. You can advertise your business and get possible customers through your website and provide informations about your products and services.

-You can also provide customer support from your website so that your customers will have the privilege to ask questions about your products and services either through forums or chat rooms on your website.

-Website can also be a medium where you can inform your stock holders, business partners and employees on the company's status, new products and services, new management or new promoted employees, etc..

? Informative/Interactive

- Many people create websites to help, inform and share knowledge with other people around the web just like this website. A good example of this kind of website is a website with either forum or a chat room wherein people can interact with each other, share works and knowledge and have fun.