When you are searching in google and want to search specific document types in Google, Google has a method to filter only the document types that is being searched for.For example if you are looking for specific document types like word documents or Excel sheets or Power point presentations or PDF documents or music files Google has a way to list only those file types in the search results. Google indexes various file formats and we can search and filter all these file formats in search results directly.When you want to search for filetype add the keywords for search and end with filetype:extension. For example Search queries can look like
invoice template filetype:docx
sales presentation filetype:pptx
For Search query invoice template filetype:docx you will see various word document templates related to invoice template
For Search query sales presentation filetype:pptx you will see various sales presentation power point documents
By Clicking the link you can download the document or view it in Microsoft Office or appropriate reader depending upon the document type.