An IPA file is an iOS application archive, containing the binary for an application along with associated resources and metadata. It is primarily used for distributing applications on iOS devices. Typically, users acquire applications through the App Store, but alternative methods exist for installing these files. These files are essentially zipped archives that adhere to a specific structure understood by the iOS operating system.
The ability to install applications from sources other than the App Store offers flexibility in various scenarios. Developers use this method for testing applications before release. Organizations distribute internal applications to employees without making them publicly available. Furthermore, users may wish to install older versions of applications or those not available in their region. Historically, this capability has been crucial for the growth of the iOS ecosystem, allowing for innovation and customization beyond the official marketplace.