Every time you send a request to the Google server in a program, you have to send your key along with it. Google checks the key and determines if it's valid, and you're still within your daily 1,000 query limit; if so, Google processes the request. The key itself is just a string of random-looking characters (e.g., 12BuCK13mY5h0E/34KN0cK@ttH3Do0R). A Perl hack usually includes a line like the following: ... # Your Google API developer's key my $google_key='insert key here';