SEM is short for Search Engine Marketing. It means that using the search engine to do the marketing. SEM is a new kind of Internet marketing form. What the SEM need to do is to comprehensively and effective use the searching engine in order to do the network promotion marketing. SEM pursuits the highest ratio with the lowest cost and acquire the largest traffic and make the commercial value. With the developing of internet ,people¡¯s life is getting more and more convenient. For example now everybody generally use the B2C website and the online pay cost and so on. All of this has apply the SEM.