Well, just like when you're feeling tuckered out, gadgets need little naps too sometimes.
Your computer does a hell of a lot all at once, especially if you're a demanding customer -- constantly streaming on Spotify, opening infinity Chrome tabs, editing in Photoshop, Slacking with coworkers, watching weird webcams. You risk using up too much RAM, or temporary memory, for everything to run smoothly all the time, especially if one of those programs glitches in any way. Restarting wipes out all that temporarily stored data, giving the software a clean slate to run normally again. And since your smartphone is basically just a pocket-sized computer, the same logic applies.
As for the other gadgets you've found yourself rebooting when things go south -- your wireless router, gaming console, Apple TV, etc. -- they all run software that can be corrupted by overuse or random interference, so a restart is like shaking a messy Etch A Sketch clean.
You've also probably heard you're supposed to unplug and wait a few minutes before booting back up. There's a good reason for that, too. Basically, this ensures the machine is completely off, since even after you've flipped the switch power may still be circulating from the capacitor (the component that regulates the flow of power from the outlet). Things don't reset until it's depleted completely.
Sign up here for our daily Thrillist email, and get your fix of the best in food/drink/fun.
Joe McGauley is a senior writer for Thrillist and has spent more time on the phone with Comcast discussing router reboots than he cares to admit.