Google.com has quietly improved its filetype: searches. Previously, it was looking (simply) for the part of a page URL that ends in the filetype: argument, and it can still do so:
filetype:tonini (finds Facebook profiles in particular).
However, for standard, common file types, Google now also searches for all files of a given kind (such as MS Excel), with a variety of extensions. I.e. Google now searches according to the “true” file format (vs. just the string in a URL after the last period). For example, consider this search:
You will be finding MS Excel files with extensions other than XLSX, such as XLS, XLTX, etc. The same is true for other standard file types such as MS Word or PDF – Google will find other file extensions. That is quite helpful for our searches. (Note that Google’s help doesn’t tell us either about non-standard extensions like tonini or searching for true file types such as Excel).
In a hurry? You can use a shorter operator ext: on Google – it works the same way as filetype:.
Check out the fully updated 4th edition of my eBook Boolean Book, that has just “shipped”. The eBook includes X-Ray templates for Sourcing – including multiple filetype: searches – as well as several new Custom Search Engines and ideas on how to search productively.