Monoliths refer to applications that have become too large and unwieldy due to a lack of discernible architecture as the application has grown over time. Rails applications are particularly susceptible due to features that enable fast development but can lead to degeneration. Symptoms of a monolith include a lack of modularity, duplication, and coupling that make the application difficult to maintain, extend, deploy, and test. It is important to break a monolith into more logical modules to gain developer autonomy, enforced modularity, and easier debugging. This can be done by splitting the application into logical modules and grouping interdependent modules together in iterations until the structure is improved. There are implementation methods like using shared databases and libraries or web services