Acronyms! Who doesn't love acronyms?
NVRAM (Non-Volatile Random-Access-Memory) and PRAM (Parameter Random-Access-Memory) are two internal Mac components that store the memory even when the device is turned off.
This is used in places like your computer's internal clock and resetting the PRAM/NVRAM can be an effective way to clear out the virtual cobwebs and get your Wi-Fi up and running again.
You should also reset the SMC (System Management Controller) while you're there for the same reason.
Resetting the PRAM/NVRAM is relatively easy:
1. For the PRAM/NVRAM, start the computer and after you hear the startup chime, hold Shift, Control, and Option keys while you press the power button on your Macbook for at least 10 seconds.
2. Immediately after you hear the startup chime, press and hold to reset the PRAM the Command + Option + P + R keys.
For older macs, release these keys after you hear the startup sound a second time; everyone else, release after the apple logo appears and disappears twice. This is also broadly true for desktop Macs.
To reset the SMC, it depends on whether you have a Mac model with a removable battery or not.
If you happen to have a removable battery, all you have to do is remove it and hold down the power button for five seconds.
On all other Macs, press Shift-Control-Option and the power button. Hold these keys and the power button for 10 seconds and release.