How can you say that Advertisement makes a product appear desirable and necessary?

Advertisements are basically a medium of attracting consumers. It is projected in such a way that consumers cannot resist desires and haunt for it in the market. Not all products which are shown in the advertisements can be bought by the buyers as price and availability do matters even if it is desirable. Sometimes, advertisements also project things as necessary without which daily life becomes difficult and creates the urge among buyers to buy them.