While the front-end interface draws a lot of attention to the general audience due to the visual interaction with it, the back-end forms the backbone of any online program. It includes the logic, data storage, and security features required to create a fully functional and reliable application. It is also responsible for processing client requests, interacting with databases, and generating responses to be delivered back to the client. There are several different responses that can be generated depending on the quality of the request. Examples of some responses include 200, 201, 400, 404, and 500. 200 OK indicates the request was successful and returns the requested data. 201 Created indicates another successful request but creates a new resource rather than displaying an existing one. 400 Bad Request indicates the server could not understand the request due to malformed syntax. 404 Not Found is a different type of client error response which indicates the requested resource could not be found. 500 Internal Server Error indicates the server encountered an unexpected condition which prevented a successful request.
The use of databases is important when it comes to designing the back end for several reasons. Data persistence is a positive outcome from databases and ensures that information is not lost when an application is closed or is restarting. It also allows for better data management and efficient mechanisms for inserting, updating, deleting, and retrieving information. Concurrency control is allowed through the use of databases, meaning multiple users or applications can access and modify data simultaneously.