What is the term for installing an app on a mobile device directly from an installation package instead of an official store?

The correct term for installing an app on a mobile device directly from an installation package instead of through an official app store is known as side-loading. This process allows users to bypass the restrictions and guidelines set by official app stores, such as Google Play or Apple's App Store.

Side-loading is often used for applications that are not available in the official stores, either due to regulation, compatibility, or geographic restrictions. It can be beneficial for developers wanting to test their applications without going through the submission and approval process or for users looking for alternative apps that offer specific features not found in mainstream offerings. However, it also introduces security risks, as apps installed this way do not go through the same vetting processes that official app stores enforce to protect users from malicious software.

The other options do not specifically refer to the action of manually installing apps from a package file. For instance, the term related to obtaining software from an official platform is app store download, while over-the-air updates refer to the process of updating software on a device wirelessly through the internet. Direct installation is not a standard term widely recognized in the context of mobile app deployments.