Search+by+site+operator

=Operator site: =

List of Domain Extensions by Wikipedia
These codes can be used with the search operator search term site:. XXX, where XXX is the domain extension to only search websites with that extension.

Here is an example of a search within only educational websites:

Google's Country Codes
These codes can be used with the search operator search term site: XX, where XX is the country code to only search websites from that country.

Here is an example of a search within only Australian websites:

Search a Particular Website
Here is an example of a search of only the SAS website: