Lang.App is an AI-powered language learning application that incorporates YouTube videos as learning material. The app's novel approach involves usage of ChatGPT to enhance the learning process by allowing users to acquire new language skills in a natural and efficient manner. The focus is on learning new words and phrases in the context of their use, encouraging users to save phrases and offering explanations for various language aspects. The key aspect to note about Lang.App is its grounding in comprehensive input approach to language learning, an approach pioneered by linguist Steven Krashen. This approach augments language understanding by presenting learners with native content, thereby making the language acquisition process feel more natural. Furthermore, the application offers a rich set of features including access to a comprehensive dictionary and engaging interactive content. It also stands out by offering these features free of charge, which typically is a paid service provided by their competitors. Through the learning journey, Lang.App seeks to blend the best aspects of AI and human-based learning to create an immersive and engaging experience for users, catering to every step of the language learning process.