Can you explain what high coupling and low coupling mean in the context of monolithic architecture?

Strong coupling means that system components are closely dependent on each other: a change in one module often requires changes in another. In monolithic architecture, this leads to difficulties in maintenance and scaling, as changes propagate throughout the application.

Weak coupling is when modules depend on each other minimally, interacting through well-defined interfaces or contracts. This facilitates system maintenance, testing, and development, as changes in one module do not directly affect others.

Example: if in a monolith, the order processing module directly accesses the user database (strong coupling), then changes to the user database structure will require changes in the order module. If, however, the order module interacts with users through a service interface (weak coupling), internal changes in the user database do not affect the order module.