Mobile High-Definition Link

Mobile High-Definition Link (MHL) is an industry standard for a mobile audio/video interface that allows the connection of smartphones, tablets, and other portable consumer electronics devices to high-definition televisions (HDTVs), audio receivers, and projectors. The standard was designed to share existing mobile device connectors, such as Micro-USB, and avoid the need to add video connectors on devices with limited space for them.

Source: Wikipedia — Mobile High-Definition Link (CC BY-SA 4.0)