What does this tool do?

This tool will query all the major search engines (Google, Yahoo, MSN) when you enter the 'link:' operator with your chosen URL. It will return the total link count for each URL.

You will notice that the totals vary greatly from search engine to search engine; this is because the figures shown represent the number of inbound-links that are known to that search engine (which will vary based on the size of their database). Most of the search engines (Google especially) also apply various filters against the inbound-links, therefore, some inbound-links may not be counted toward the total.