Apple ships a little-known utility app that helps you analyze and diagnose your Wi-Fi connection, called Wireless Diagnostics. Open the app by option-clicking on the Wi-Fi indicator in the menu bar and select ‘Open Wireless Diagnostics …’. Although the app contains a lot of useful information, it isn’t intuitively clear what you are supposed to do with it.
Frustrated by bad WiFi on Mac OS X? This guide may help you get better WiFi on your computer.