SEO Vs SEM

can anyone tell me what is the difference between SEO and SEM?

SEO is to make the website rank high on SERPs. Link building is used to make this goal a reality. Building more good quality links increase this chance. SEM is promoting the website to increase its visibility on SERPs. Just think SEM as the marketing manager and SEO as his tools.

[FONT=Verdana]This question has been asked and answered many, many times before. Please read the SEO FAQ or use the [url=http://www.sitepoint.com/forums/search.php]Search facility to find past discussions.

If, after reading those, you’ve still got any specific questions that haven’t been answered, please do come back and start a new thread. In the meantime, I’m closing this one.[/FONT]