Terms

Question 1

Idempotent

Answer 1

Making multiple identical requests has the same effect as making a single request.

Question 2

Idempotent requests

Answer 2

GET, PUT, DELETE, HEAD, OPTIONS, and TRACE

Question 3

Cross-Origin Resource Sharing (CORS)

Answer 3

1. foo.com requests OPTIONS method on bar.com
2. bar.com sends a header like Access-Control-Allow-Origin: http://foo.com in response to the client
3. Next, foo.com can access the resources on bar.com without any restrictions that call any REST method