In the context of a web application, the backend is the part of the application that handles requests from the client side (frontend), provides business logic execution, and interacts with databases and other external services. Typically, the backend includes the following components:
Server logic:
This is the code that runs on the server and handles requests from clients. It may include request routing, data processing, authentication, authorisation and other business logic.
Databases:
The backend usually interacts with databases to store and retrieve data. This can be a relational database (e.g. MySQL, PostgreSQL) or a NoSQL database (e.g. MongoDB, Redis).
Authorisation and authentication:
The backend can manage user authentication (validation) and authorisation processes for access to various application resources.
External services:
The backend can interact with other external services or APIs to perform additional functionality such as sending emails, processing payments, working with external APIs of third-party services, etc.
API (Application Programming Interface):
The backend usually provides an API that allows the frontend to communicate with it. This can be a RESTful API, GraphQL API or another type of API.
Thus, the backend is the server side of a web application that provides data processing, execution of business logic, and interaction with databases and other external services