Advances in software engineering had shortened the time needed to build an application from scratch. For instance with Spring Boot, I can easily build my own web API backed by a web server of my choice into a single jar file. By running that jar file, I can start a process that responds to HTTP requests directed at my customized endpoints.
However, not knowing how that jar file is formed and read by the Java Virtual Machine can cloud our understanding of application development with Java. To help understand Java application development better, I described how to manually create a jar file for running a Java application.