Expo is a software development platform that provides an open-source framework for building native applications across Android, iOS, and the web using JavaScript and React. It offers a full-stack environment that includes development tools, libraries, and cloud-based services to support the entire application lifecycle, from coding to deployment and updates. The platform includes a software development kit (SDK) with pre-built modules that enable access to device features such as cameras, notifications, and deep linking. It also provides building services, submitting, hosting, and updating applications, along with workflows that automate testing and release processes. Additionally, Expo includes monitoring and analytics capabilities that allow developers to track application performance, usage, and errors after deployment.