The first part describes the functions and business of electronic commerce like a modern way used in developed countries. The first part describes the pros and the cons when a business is done that way, the risks electronic business brings with it, and what are the efficient measurements from keeping the abuse of information safe. Also, there are descriptions of some business models that can shorten the risks, systems of paying from distant places, order processing and the final shipping of products. The second part describes modern ways of marketing and advertising via the Internet and what advertising methods on the Internet exist. Marketing via the Internet greatly reduced the cost of advertising, and online marketing it is the most common choice for smaller companies, instead of the traditional way.The biggest advantages that online marketing brings with it are small advertising costs and a wide range for the presentation of products and services.The third part describes the business and advertising of one of the most successful and best-known online commerce companies today, under the name of eBay, which operates with a growing tendency and constant expansion of the market. Also, the paper mentions which is the most widely used method of payment, and how to become a user of e-commerce. Large companies also require capable programs that successfully advertise their name on regions around the whole world, and for that reason, it is described how an advertising program functions for a company.