Most people visiting this page are interested in marketing either some specific product such as an invention, or else interested in setting up their own web site and marketing from there. The difference between promotion and marketing.
Visibility is a real problem with the Internet.
True, it is a huge market place of roughly 100 million people, but equally, there is so much to look at that your goods are all but invisible to start with, however well packaged. Therefore, the first thing to do before you would even contemplate selling, is to put your wares on show so that people become aware of their existence. Promotion is therefore mostly concerned with making people aware of your product. It is more than mere advertising, as the Internet is an interactive medium and your visitors will often comment, or ask questions. An other point is, that you have far more space for explaining your product and also illustrating its more important points by using photos, drawings, and the occasional animation.