Why is the .env file needed?

Question

React

In Google, I have already read, in principle, they write that for storing variables and their values.
I do not fully understand what is the benefit of this file with variables. Does this file serve as protection or just for convenience? I will be glad to any answers.

Answer 1

.env files usually contain environment variables, and for different environments like dev, production, staging, different files can be created. Also, each of the developers can change the variables on the local system for themselves at their discretion.
In general, env files serve to isolate an application from the environment in which it runs. Some kind of configuration abstraction.
For example, it usually stores all sorts of API keys and other passwords that developers do not want to stick into the code (for privacy purposes, for example, if the project is open-source and all the code is uploaded to GitHub).