Apple today have released a myriad of updates at the front of these is iOS12 and watch OS5.
Checkout your updates for apps on your devices as well.
It is a large update – just over 1.5 gb so make sure you have enough room to install it.
I have been running iOS12 for a while now and have had no issues – iOS12 will also improve performance on older iOS devices.
Here are some links to assist: