Do I need to re-submit to the search engines if I change my Web page code?
Not necessarily. Search engines' spiders revisit indexed Web pages at predetermined intervals. Code changes will be detected and reflected in the page ranking upon next visit. On rare occasions, re-submitting a page might ensure that the engine detects the changes faster than it would by relying on the spider's scheduled crawl. Note that not all engines allow resubmission of URLs.