What is the difference between HTTP PUT and PATCH requests when updating resources?

HTTP PUT and PATCH requests are used for updating resources but differ in meaning and application:

• PUT — complete update of a resource. When sending a PUT, usually the full set of resource data is transmitted, and the server replaces the existing resource with the new one. If the resource does not exist, it can be created.

• PATCH — partial update of a resource. Only the set of changes or fields to be updated are sent, without replacing the entire object.

Example:

PUT /users/123
Content-Type: application/json

{
  "name": "Ivan",
  "email": "ivan@example.com"
}

Will replace the entire user 123 resource with new data.

PATCH /users/123
Content-Type: application/json

{
  "email": "newemail@example.com"
}

Will only update the email field of user 123.

The choice depends on the task: use PUT if you need to replace the entire object, use PATCH to update a part.