Using Google more efficiently part V: file type and similar search

Posted by Greten on 03 May 2013 under Tools

This entry is the fifth and final part of a serial post about using Google more efficiently for your research. Click here to get an overall preview of what this topic is all about although you may also proceed in reading this article. You will still understand it without reading the introduction part.

In the second part, we discussed the Boolean operators, in the third part we discussed the exact search and wild card that is frequently used with it, in the fourth part we discussed how to limit the search on specific sites and top level domains. This last part will discuss two more operators that you can use to conduct search in Google more efficiently: the file search and the similar search. They are hardly related but they are all that remains.

Search specific file type

icons for word processor document, spreadsheet, and portable document format with Google search resultsTo search for specific file type, you need to use the 'filetype:' operator. It is somehow similar to 'site:' except that what you need to type on the right side of the colon is the file extension of the filetype you are looking for. File extension is that three-letter string (in some cases four) that's on the right side of the dot in a filename. For example, a document file in Open Document Format produced by OpenOffice or LibreOffice will usually end in .odt. Here, odt is the file extension.

This can be particularly useful if you notice that most of the information you're looking for are in certain file types and would like to limit your search in those file types. For example, you are looking for math addition worksheets and you noticed that many of them are in PDF format (with file extension of pdf). You decided to filter all the other results so you can see only the PDF files. You can encode the following in the search box:

math addition worksheet filetype.pdf

You can also use the OR operator to search for two or more filetypes.

math addition worksheet filetype.pdf OR filetype.odt OR filetype.doc

You may also use dash(-) as negation to remove certain file type from search results.

math addition worksheet -filetype.doc

Similar search

The similar search acts as some sort of thesaurus. It tells Google to return results not just those containing the exact keyword but also keywords related to it. The syntax for similar search is to have tilde (~) on the right of the keyword. There should be no space between the tilde and the keyword.

For example, typing the following in the search box:


... will return results not just those web pages that contain the word "knowledge" but also those that contain the word "learning".

The similar search works only as lone word or in conjunction with other words ([either with OR operator or the default AND]) but not in exact search. If you typed a phrase enclosed by double quotes in the search box and one of those words has tilde, the search results will be as if there is no tilde.


This completes our discussion on how to use Google more efficiently for your online research. As I said in Part I, some of these may also work in other search engine. In particular, I tested the domain search on Yahoo and it worked, but the TLD search did not.

Please share to us if you have some other techniques in making research on the internet more efficient. If you followed my tips here and it seems that Google is not working in the way I explained here, please leave a comment so that I could investigate what happened and others would know.

Last updated on 09 Dec 2018.

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