By default, the iPhone keyboard is set to make a clicking noise every time you press a key. Some people like it, but for others the sound of someone tapping away at a text message can be pretty annoying.
The clicking won’t sound when you have your device muted, but at other times it can be bothersome.
To turn it off permanently, open Settings and select Sounds & Haptics, then Keyboard Feedback. Turn off Sound to silence the clicking, and turn on Haptics if you’d like to feel tactile, physical feedback when you type instead.
Now you can text away to your heart’s content without those pesky noises!