In the context of EC2 instances, what does ‘initialization’ refer to?

Initialization in the context of EC2 instances refers to the process of preparing the instance for use after it has been launched. This encompasses several steps necessary to ensure that the instance is fully ready to serve requests, including the execution of startup scripts, installation of software, configuration settings, and any other preparatory activities specified in the User Data script.

During initialization, the operating system is loaded, and the instance transitions from being just a virtual environment that has been created to an active server that can run applications and respond to network requests. Therefore, while the operating system booting up and the configuration phase are components of the overall initialization process, they do not encapsulate the full scope of what initialization entails. Initialization covers all preparatory actions needed beyond simply booting up or configuring the instance, making it a broader and more comprehensive term in this context.