Modulith architecture is a style of software design that emphasizes modularity within a monolithic application. It aims to combine the simplicity and straightforward deployment model of a monolithic architecture with the modularity and maintainability typically associated with microservices.

In a modulith, the application is structured as a collection of loosely coupled modules, each encapsulating a specific business capability or domain. These modules interact with each other through well-defined interfaces, yet they are deployed as a single unit, similar to a traditional monolithic application.