Why do you need a Bing keyword tool? Bing—Microsoft's competitor to Google—is gaining in market share, and it's no longer enough to simply optimize for Google and ignore the other search engines. There are appreciable differences between Bing's algorithm and Google's algorithm, and you may find that your website ranks better in Bing than in Google or vice versa. Likewise, it's possible that Bing users search for and find your site using different keywords than Google users.
Luckily, the basic principles behind Bing optimization, for the most part, are similar to those for Google. The process of optimizing your site and your pay-per-click advertising for any search engine starts with keywords. Well-executed keyword research will provide a strong foundation for all your Internet marketing efforts.