Difference between SEO,SEM and SMO?

[Bhupender Pal]

Search engine optimization & search engine marketing both the terms actually refer to two different parts of the same marketing scheme.SEM is a much broader term than SEO, and actually includes SEO as one of its techniques. SEM is all that a company can do to advertise itself on a search engine, including paid inclusion and other ads.

So dear friends, what do you think about these term?