Search engine crawlers and indexers are basically software programs; powerful computer programs that crawl billions of web pages, analyse these pages and the way that they all link together. Any changes to your site (such as URLs, content or links ) will be viewed through the eyes of these robots and changes to their index made accordingly. You won’t be notified if anything that you do may be going to cause problems. You’ll just find out a few days/weeks/months after the event when your pages drop in the SERPs or disappear from the listings all together. Finding a job as a UK SEO Consultant isn't easy!