Update 10/21: Bing's homepage in the U.S. and Australia now has a new feature that enables users to switch to "full screen," with just a single click on the "Full Screen" button, all navigational elements from the top and bottom will fade away, leaving you with only the Bing homepage photo or video, the search bar, and the "hotspots".
Check the screenshot below:
Bing offers various advanced query operators, helping bing.com customers and Bing API customers to refine their query to match their needs. Two of these operators - filetype: and ext: - appear to be same but there are subtle differences.
One of the most commonly used operators is "filetype:" which helps to filter documents in search results based on their particular filetype include: html, txt, and pdf, as well as the primary Office document types: doc, rtf, xls, and ppt for Word, Excel, and PowerPoint documents. For example, "1040 filetype:pdf for the official IRS 1040 for US Taxes," Bing explains.
Another operator "ext:" is helpful for finding URLs ending in specific formats… for example, template ext:docx will filter search results to URLs having extension .docx.
The key difference between these two operators is, "filetype: operator is based on classification of the content associated with URLs, and the bing ext: operator is only based on the URL file extension. Also, the Bing filetype: operator is based on our classification of the content associated with URLs, and the Bing ext: operator is only based on the URL file extension," explains Bing.
These operators are also useful for webmasters to audit files indexed within their site via site:wikipedia.org filetype:pdf.