PART IV · BACKEND
Backend
The part of a software system that processes requests, applies logic, and works with data behind the interface.
01
What is it?
The backend is the part of a software system that runs behind the user interface.
It receives requests, applies business logic, works with databases or external services, and returns results.
Simple Definition：
The backend is where the system processes work behind the screen.
02
Think of it like...
Think of a restaurant.
The frontend is the dining area where customers place orders.
The backend is the kitchen where the work is processed.
Flow:
FrontendBackendDatabase / ServicesResponse
03
What does it do?
The backend can:
Validate Data
Apply Business Logic
Read and Write Data
Call External Services
Return Responses
04
Where is it used?
Backend systems are used in:
Web Applications
Mobile Applications
APIs
Trading Platforms
Payment Systems
Enterprise Systems
05
Example
Scenario:
A user creates an order.
Flow:
FrontendPOST /api/ordersBackendValidate DataApply Business RulesSave OrderReturn Response
06
How it connects
Flow:
FrontendAPIBackendBusiness LogicDatabaseResponse
The backend connects user actions with system rules, data, and other services.
07
Do Not Confuse
Backend
Processes requests and data behind the interface.
Frontend
Displays information and interacts directly with users.
Frontend = What users interact with
Backend = What processes the work
08
Topic Glossary
| ENGLISH TERM | 中文 | SIMPLE ENGLISH | 中文小白理解 |
|---|---|---|---|
| Backend | 后端 | The part of software that processes requests and data behind the interface. | 在界面背后处理请求、业务逻辑和数据的系统部分。 |
| Backend Application | 后端应用 | Software running on the backend. | 运行在服务器端、负责处理系统逻辑的程序。 |
| Business Logic | 业务逻辑 | Rules that determine how business operations work. | 决定系统业务如何处理的一组规则。 |
| Database | 数据库 | A system used to store and manage data. | 用来保存和管理业务数据的系统。 |
| API | 应用程序接口 | An interface used for communication between systems. | 前端或其他系统与后端通信的接口。 |
| Request | 请求 | A message asking the backend for data or an action. | 客户端发给后端、要求查询或执行操作的信息。 |
| Response | 响应 | The result returned by the backend. | 后端处理完成后返回给客户端的数据或结果。 |
| Server | 服务器 | The computing environment where backend software often runs. | 后端应用通常运行所在的计算环境。 |
09
What to Remember
The backend processes work behind the user interface.
It connects APIs, business logic, databases, and external services.
The frontend sends requests; the backend processes them and returns responses.
Final:
FrontendBackendData / LogicResponse