Dark Mode

Dark Mode darkens the user interface of iOS, iPadOS, macOS, and tvOS, with lighter type on darker backgrounds to reduce eye strain, especially when used in a darker setting.

History
A partial implementation, which was limited to the menu bar and Dock, was introduced in OS X 10.10 "Yosemite", which was released in October 2014. It could be enabled through the General System Preferences pane. It is also possible to enable only a dark Dock and leave the menu bar bright through some Terminal commands.

A system-wide implementation of Dark Mode was first introduced in 2018 as part of macOS Mojave (10.14). It was introduced as part of iOS 13 and iPadOS 13 in 2019.

3rd party utilities
Dark Mode for Safari is a 3rd-party extension that enables Safari to darken websites that use light backgrounds.