Mostly we write SEO for Search Engine Optimization and SEM for Search Engine Marketing. These are two different names but having 80% same functionality and concepts of web site optimization. In the world of internet every day we are facing different new technologies and web based applications appearing.

Similarly there are some technologies are invented in website optimization field. One of them is SEO and second one is SEM. SEO is the subset of SEM because in SEM we get the SEO results. So many people having Search Engine Optimizing experience prefer SEM as compared to SEO.

Two years later in the world there were hundreds of companies and organizations those were working for SEO techniques. But now the trend has changed, new discovery has been made in Search Engine Optimizing field. SEM has taken the place of SEO.