The sprouting of Internet brought unquestionable advantages, because one has become a powerful tool for the entire world. Being it did not exempt of these advances of evolution the branch of the commerce, that is to say what we called at the moment as electronic commerce. Considered as the purchase and sale of products or services through electronic means, such as the Internet and other networks of computers. Internet has caused to a great extent the extraordinary growth of this means of negotiation. Because the Web offers certain types of this interchange as well and the possibility of to participate in an interactive market, in which the costs of distribution or sales tends to zero.
Buying and also selling they are contacted to each other of direct way, thus eliminating restrictions that appear in such interactions. This way, one obtains publicity, promotion and service to the client custom-made by means of the Web that in the same way offers the opportunity to compete on the base of the specialty, instead of to do it by means of price, since from the point of view of the trade, rarely he is desirable to compete only based on the price. The electronic commerce tries to satisfy the needs with the clients on the basis of the benefits that they look for, which means that the price depends on the valuation of the client, and not of the costs; such opportunities arise when offered the difference by elements of trade different from the price, which produces loaded benefits of value, like for example, the comfort produced by the direct distribution by means of the electronic distribution of software. With all these new concepts they are created different ways in the ample world from the commerce as they are it the pages of announcements classified. These are sites where announcements are inserted free on supplied products, and they are possible as well to be consulted what they offer other people, that is to say in these places we can be clients or salesmen to the same time. Most common it is than the product range is very varied, since in them free we found classified announcements of purchase and sale of moving bodies, floors, houses, cars, computers, motorcycles, use, clothes, furniture, crossings, animal, second hand, all this to passages of click, and the best thing is the interaction between the user and the system since she is extremely simple.