You see, it is a simple mathematics. The Internet is the biggest singular marketplace today. In 2010, there will be estimated 1.93 billion Internet users and a billion of mobile Internet users. In 2015, this is set to rise to 2.51 billion Internet users and 1.65 billion mobile Internet users. This shouldn't be a surprise to anyone of you! With the progression of China (already the largest online demographic), India and Latin America, the growing popularity of smartphones and increasing expansion of broadband connections, the Internet is growing faster than any other medium in the HISTORY of mankind.
The first and foremost answer is: To establish a presence. Close to 3 billion people world-wide have access to the World Wide Web. No matter what your business is you can't ignore 3 billion people. Even if you just conduct business within your community, you want to let people in that community know that you are interested in serving them in any way possible. If you don't, your competitors will.
The next good reason to put your business on the web is: to network. A lot of what passes for business is nothing more than making connections with other people. Every smart business-person knows; it's not what you know, it's who you know. Passing out your business card is part of every good meeting and every business-person can tell more than one story how a chance meeting turned into a big deal. What if you could pass out your business card to thousands, maybe millions of potential clients? You can do this 24 hours a day, inexpensively and simply, on the internet.
You can also make business information available to everyone who wants it without any additional effort. You can give them answers to questions like: What are your hours? What do you do? How can someone contact you? Where are you located? What are today's specials? If you could keep your customers informed of every reason why they should do business with you, don't you think you could do more business? You can on the internet.