What is an SEO, SEM and how important are they for an organization? Explain briefly.

Ans: There is a lot of helpful information, as well as a lot of misinformation, floating around regarding search engine optimisation (SEO) and search engine marketing (SEM). First of all, let's start with the names: SEO stands for search engine optimisation (or optimization if you're from the States). In its simplest form SEO is the process of tailoring a website (text, titles, meta tags, alt tags, etc) so that the search engines will assign a good rank to the site for specific search terms.
But with the advent of search engines introducing fees for guaranteed inclusion in their indices, directories charging for reviews and the emergence of PPC listings, SEO now has an element of media buying mixed in. Thus, thanks to Danny Sullivan, it has now been called search engine marketing or SEM (you can still call it SEO if you want).