Backend application

The part of a system that executes on the server side and has the responsibility of managing data and serving client applications’ requests.

Main components

Server

a big/powerful computer

should be live 24/7, always listening for any requests - and connected to the internet, ready to receive requests.

But it’s the application running on the server that actually processes those requests and decides how to respond.
traditionally, servers are made and optimized for this particular purpose, but at the end of the day, any computer that is connected to the network can act as a server
(Think AWS, DigitalOcean, or even your local machine during development.)
- Node.js - provides the runtime environment that executes your JavaScript code on the server

Application

all the logic that enables the web app to function & determines how you want the server to respond to the requests from the browser

This is where your backend framework (e.g., Express.js, Next.js (fullstack! both frontend and backend!), Django, ASP.NET) comes in. It handles requests, processes data, and sends responses.
it can respond with different things other than HTML
- data
- status code (404 - request invalid - application doesn’t know how to respond with the request)

permanent storage for web application
can store/retrieve user data
not a requirement, but becomes necessary as applications get more and more complex/larger
Common databases include MySQL, PostgreSQL, 🍃MongoDB, etc.
db는 백엔드 개발자에겐 심장과 같음 ㅋㅋㅋㅋ 그냥 무조건임…
Related:Databases (AWS)
🗃️Database

diagram
In order to communicate between the client-side and server-side, we need HTTP requests that come from the client to the server

Client side
- the side which the user is going to access and interact with ur website
- desktop, laptop, mobile, etc
- Asks for a Request
  - It’s when a device asks for a resource (data, image, HTML page, authentication token, etc)
  - Requires a connection to the internet (wired, phone, smart connection, etc)
Server side / server
- everything in the backend
- computer running server code, application, database
- Sens a response
  - The reply to the request
  - Could contain the resource (HTML, JSON, data, etc) asked for by the client
  - Could contain a response saying that the client is not authorized (401)

user types in google.com
this request goes thru the internet to google’s servers somewhere in the world
on the server computer, there is an application running, listening for this particular request
once it finds it, it sends back the homepage (index.html + css + js + etc) to the client