anybody tells me Difference Between SEM and SEO?

and which one is more important for a travel site.

Thanks

Anamika

SEM encompasses all you do for your site, to rank highly in the search engines and to attract the most traffic, which in turn means higher conversions.

SEO is a part of SEM which emphasis optimizing your site so that it ranks highly in the natural search results (not the top or the right side) of search engines. SEO is all about relevance. If the search engine, based on (for google) its 200 or so variables considers your site relevant enough, based on keywords, then you rank highly, compared to the competition.

The other part of SEM is PPC (like google adwords). You bid for certain keywords and provide a budget and your ad shows up either at the top of the page or the right column for as long as the clicks you are paying for doesn't exceed your budget.

It might be worth noting at this point that google for instance, places emphasis on research-based sites so for a travel site like yours, you might want to consider placing a higher emphasis on PPC, to help boost your conversion rates.

good luck!