React Native is a cross-platform native mobile app development framework created by Facebook based on their React JavaScript library. It allows developers to build mobile apps using React Native components, which are then compiled into native apps that are almost identical to apps written using native tools. Facebook uses React Native for several of its own apps, including the social media network, Facebook Ads Manager, and F8 app. Other popular companies like Instagram, SoundCloud, Tesla, Uber, Skype, Pinterest, Discord, QQ, Bloomberg, Google's Grasshopper, Unacademy, 2048, CBS, Vogue, Hive, Gyroscope Health, Discovery VR, Wix, KFC UK, delivery.com, Chop, adidas GLITCH, Myntra, Townske, Artsy, and MoneyLion also use React Native for their mobile apps.