Monolithic applications typically consist of multiple components that are interconnected to form one large application. These components may include these features:

Authorization. To authorize a user and allow them to use the application.

Presentation. To handle Hypertext Transfer Protocol requests and respond with Hypertext Markup Language, Extensible Markup Language or JavaScript Object Notation.

Business logic. The underlying business logic that drives the application's functionality and features.

Database layer. Includes the data access objects that access the application's database.

Application integration. Controls and manages the application's integration with other services or data sources.

https://martinfowler.com/bliki/MonolithFirst.html