What are CRUD operations, and how do they map to HTTP methods?

Question

Accepted Answer

CRUD stands for Create, Read, Update, Delete, the four basic operations of any data store. They map to HTTP as Create → POST, Read → GET, Update → PUT/PATCH, Delete → DELETE.
Databases and applications all store and change data with the same four operations, and HTTP's methods line up with them:

CRUD
HTTP
Example on customer data

Create
POST
Insert a new customer record

Read
GET
Fetch a customer's home address

Update
PUT / PATCH
Change the stored street address

Delete
DELETE
Remove a customer

This mapping is what makes REST feel familiar. A network device exposed through a REST API behaves like a database of configuration: you create, read, update and delete entries, and the device applies them.
Go deeper:

Create, read, update and delete — Wikipedia — CRUD across SQL, HTTP and other systems.

CRUD	HTTP	Example on customer data
Create	POST	Insert a new customer record
Read	GET	Fetch a customer's home address
Update	PUT / PATCH	Change the stored street address
Delete	DELETE	Remove a customer