You probably know about the mute switch on the side of your iPhone, and you may even know about the Do Not Disturb feature. These features may seem to do more or less the same thing--keep notifications from bugging you--but they have a few distinct differences.
The mute switch simply mutes the device's audio. Turn it on, and you won't hear incoming alerts, calls, and other notifications. The problem with the mute switch is that it is on until you turn it off, which means if you get an important call or text from someone, you may not hear it when it happens.
Do Not Disturb (DND) on the other hand, let's you do a bit of configuration regarding what notifications you do and don't get, and when things are silenced.
There are two ways to turn on Do Not Disturb: manually and on a schedule. To turn it on manually, drag up from the bottom of your screen to access the Control Center. Tap the moon icon. You'll see a moon symbol in the upper-right corner of your device's screen.
To enable it on a schedule, head to Settings > Do Not Disturb. In the screenshot below, the "Manual" switch is set to On, which means we've set it manually. If you instead flip "Scheduled" to on, you'll have the option to turn Do Not Disturb on at certain times (say, when you're sleeping) and off at others (like during the day).
You'll also see quite a few options that make it stand out from the simple mute switch. For example, you can set it to always allow calls from certain contacts, or allow repeated calls from the same person (say, in the case of an emergency) You can also tell it to silence notifications only when your phone is locked..
In short, the mute switch is best used for the short term, such as when you're going to the library or watching a movie at theater, while Do Not Disturb is best for times when you expect to use it, such as before you go to bed or at work.
If you find Do Not Disturb fits all your needs and you don't need the mute switch, you can change the function of the mute switch if you're using an iPad. It can either operate as intended, or you can change it to lock your tablet's rotation.