[Stateful Applications]
Stateful applications are applications that store data and keep tracking it.
All databases such as MySQL, Oracle, PostgreSQL are examples of stateful applications.

[Stateless Applications]
Stateless applications are applications that do not keep the data.
Node.js and Nginx are examples of stateless applications.
For each request, the stateless application will receive new data and process it.

[Integration with Stateful Applications & Stateless Applications]
In a modern web application, the stateless application connects with stateful applications to serve the user’s request.
A Node.js application is a stateless application that receives new data on each request from the user.
This application is then connected with a stateful application such as a MySQL database to process the data.
MySQL stores data and keeps updating the data based on the user’s request.

# EXAMPLE 1 :-
User (PC)   <----->   Node.js application   <----->   MySQL
 Browser              Stateless Applications          Stateful Applications

# EXAMPLE 2 :-
                                Load Balancer
                                       |
                                       |
                      -----------------|-----------------
                      |                |                |
                      |                |                |
                      |                |                |
                     Web              Web              Web
                 Application      Application      Application
                 (Stateless)      (Stateless)      (Stateless)
                      |                |                |
                      |                |                |
                      |                |                |
                   Database         Database         Database
                  (Stateful)       (Stateful)       (Stateful)