This search operators restricts the results to items of a specific type. Entering puppies filetype:jpg will get you lots of puppy pictures
Finds pages containing a specific string of text. For example, Beatles breakup intext:Paul McCartney finds pages containing Paul's name and the words Beatles, breakup, or both. The operator allintext goes at the start of the search field and forces Google to return only those pages that contain all of the following search terms
Similar to intext, search for specified terms in the title of webpages
Similar to intitle and intext, but works on URL
finds pages linked to the specified URL. link:fengqijun.me will find pages linking to my blog
Finds pages similar to the one you specified; iOS related:fengqijun.me
This is perhaps the handiest, as it finds the search terms on specific website.