Charging is on Hold right now

Your phone hasn’t overheated; you can still use it.

Let’s define “overheating”. If an iPhone overheats it shuts down so it can’t be used, and displays a message saying it must cool down before it can be turned on, and it will probably be unusable for an hour or so. If you are seeing this it is a hardware problem and you should contact Apple support: 

• Click on “Support” at the top of this page
• Go to Contact Official Apple Support

Note that both of the above have options to receive a callback or chat

If you are not seeing this your phone has not overheated. However, if you fast charge your phone may pause charging somewhere over 80% and display a message saying that charging has paused, and will resume when the phone cools down. This is NOT overheating, and is normal when fast charging.

Also, some apps that use a lot of energy or that use cellular data rather than Wi-Fi can cause the phone to run warmer.

If your iPhone or iPad gets too hot or too cold - Apple Support

If this message appears on the Lock Screen: "Charging On Hold. Charging will resume when [device] returns to normal temperature."