Install iOS 13 Beta for Dark Mode
Dark Mode is one of the biggest improvements on board iOS 13 and it's a great reason to try out the iOS 13 update ahead of its official release.
In a nutshell, Dark Mode is a new dark color scheme that works across the iOS platform, including native apps, to give you a better viewing experience, particularly when you're in low light environments. It makes the content on your iPhone's screen much easier on the eyes.
It's similar to the Dark Mode Apple introduced to Mac with macOS Mojave.
For more on Dark Mode, take a look at the video above.