Chromecast is a line of digital media players developed by Google. The devices, designed as small dongles, can play Internet-streamed audio-visual content on a high-definition television or home audio system. The user controls playback with a mobile device or personal computer through mobile and web apps that support the Google Cast protocol, or by issuing commands via Google Assistant. Alternatively, content can be mirrored from the Google Chrome web browser on a personal computer or from the screen of some Android devices. The first-generation Chromecast, a video streaming device, was announced on July 24, 2013, and made available for purchase on the same day in the United States for US$35 (equivalent to US$38 in 2019). The second-generation Chromecast and an audio-only model called Chromecast Audio were released in September 2015. A model called Chromecast Ultra that supports 4K resolution and high dynamic range was released in November 2016. A third generation of the HD video Chromecast was released in October 2018. The latest model, called Chromecast with Google TV, was released in September 2020 and is the first in the product line to feature an interactive user interface and remote control. Critics praised the Chromecast's simplicity and potential for future app support. The Google Cast SDK was released on February 3, 2014, allowing third parties to modify their software to work with Chromecast and other Cast receivers. According to Google, over 20,000 Google Cast–ready apps are available, as of May 2015. Over 30 million units have sold globally since launch, making the Chromecast the best-selling streaming device in the United States in 2014, according to NPD Group. From Chromecast's launch to May 2015, it handled more than 1.5 billion stream requests.