When you turn a piece of equipment off and then right back on again it is known as a power cycle or power cycling. In the modern era of electronic equipment this is a common technique for clearing out registers or operational parameters that can become corrupted and cause erratic behavior or system crashes. It has also been used as a technique for getting out of a mode of operation from which the user sees no other escape. For example, if you get 15 layers down into editing your synthesizer and have no idea how to get back out or undo everything you just did, a power cycle will often return you to a default state (though not always, some equipment powers up in the exact same state it was when turned off). Usually if the machine has a routine where it boots up – meaning loads an OS in each time it is turned on – then a power cycle will be enough to return you to the top layer of menus as well as correcting some erratic behavior you may have encountered.