Installation

Installation is the process of obtaining a copy of software and placing the appropriate files in the system from where it could run. In order to standardise this process, there are multiple strategies of installation, primarily concerning:
installation app or script: a special program that user downloads and invokes that guides user through all the steps, asks questions and requires them to subscribe to the licence. This method is primarily used in the Windows ecosystem and has been criticised for its powerful vulnerability and relying on the good faith of script distributor. Nonetheless, it is sometimes used as a way to bootstrap an application or package used by developers.
package manager: a program that is locally installed on a machine and can install other applications by downloading their package from the entrusted domain (usually the package manager distributor) and configuring it to be visible by the OS. This method is primarily used by Unix-like operating systems such as Linux distributions and MacOS.
mobile stores: programs that come with a mobile OS that too, install an app through an entrusted Internet source. The difference with package managers is that while mobile stores do it graphically and only require users to press the download button, package managers tend to be terminal-based and require a confirmation when all the metadata is collected.
embedded installation: there are various means that allow software to be installed without assistance of other apps, primarily in an environment that lacks OS and runs on bare metal. These cases often involve embedded engineers that install software, including OSes, by flashing, burning or otherwise imprinting it on hardware manually. [1, 1-3].

Sources:

M. Bajer. (2014). Embedded software development in research environment. A practical guide for non-experts. Montenegro: 3rd Mediterranean Conference on Embedded Computing.

A. Varun, M. R. Patil, P. Kantanavar & G. Shobha. (2019). A Comparative Study of various Linux Package-Management Systems. Advances in Computational Sciences and Technology, 12(1), 37-42.