To look up a QRZ callsign, go to the website QRZ.com, click on Advanced Search under the Database drop-down menu, and enter a search term, choosing the type by callsign. When searching, an asterisk may be used as a wild card; for example, "W1*" returns all W1 calls, and "*XX" locates all calls ending in XX. You can also search by name, address, biographical information or grid square locator to find the callsigns for operators meeting those criteria.
QRZ.com also has a list of Hot Callsigns under the Database drop-down menu. The list is composed of users who have had the greatest number of lookups in the 10 minutes prior to clicking on the menu item. The list draws from both XML and Web clients.
The website database provides other information such as expired callsigns and just-added callsigns. Click on the menu item Random Callsign to find information on an operator you might not have run across before. If you prefer to peruse the database offline, the website offers an option to download all or part of the database in a compressed ZIP file.
QRZ.com is the world's leading amateur radio callsign database as of 2015, and it also provides news, technical articles, discussion forums, an online swap meet and other resources for ham radio operators.