Once your wireless router is set up, all of your devices will remember the Wi-Fi password automatically. While this is convenient, it can be problematic if you've forgotten the password -- especially when it comes time to set up a new device on the network. Fortunately, it's possible to look up your Wi-Fi password without resetting the router.
- Open the "Keychain Access" app in the Utilities folder. (Alternatively, you can click the Spotlight logo in the upper righthand corner and type "Keychain Access" and open it from there).
- Search for "Airport." This brings up a list of all the networks your computer has connected to.
- Find your router's name in that list, and click "Show Password."
If you're unsure of your router's name (SSID), just click on the Wi-Fi logo in the menu bar, and you'll see a check mark next to the name of your network.
Since the steps vary depending on the version of Windows you're running, consult this Microsoft Support article. This has detailed instructions for finding your Wi-Fi password on Windows 8.1, Windows 8, or Windows 7.