Package Management
When working in complex systems, especially in microservices or similar architectures, there is sometimes a need to share code so it's available at different, unconnected parts of the system. That's normally code that will help to abstract some functions, which can vary greatly, from security purposes (for example, calculating a signature in a way that's understood by other systems that will have to verify it), to connecting to databases or external APIs, or even helping to monitor the system consistently.
Instead of reinventing the wheel each time, we can reuse the same code multiple times to be certain that it's properly tested and validated, and consistent throughout the entire system. Some modules may be interesting to share not only across the organization but even outside it, creating a standard module others can take advantage of.
Others have done that before, and a lot of common use cases, such as connecting to existing databases...
