Question 1

What is the difference between GET and POST?

Accepted Answer

GET retrieves data without modifying server (safe, cacheable, no body). POST creates new resource (unsafe, not cacheable, has body). GET parameters in URL query string. POST data in request body. GET can be bookmarked and cached. POST cannot. Use GET for reading data, POST for creating resources.

Question 2

What is the difference between PUT and PATCH?

Accepted Answer

PUT replaces entire resource with new data (full update). PATCH partially updates specific fields (partial update). PUT requires complete resource data. PATCH only needs changed fields. PUT is idempotent (same result repeated). PATCH can be idempotent if designed correctly. Use PUT for full replacement, PATCH for partial updates.

Question 3

What HTTP methods are idempotent?

Accepted Answer

Idempotent methods: GET, HEAD, OPTIONS, PUT, DELETE. Same request multiple times produces same result. Not idempotent: POST (creates new resource each time). PATCH can be idempotent if designed correctly. Idempotency important for retry logic and caching. Safe methods (GET, HEAD, OPTIONS) are always idempotent and don't modify server.

Question 4

When should I use DELETE method?

Accepted Answer

DELETE removes resource from server. Use DELETE for removing data. DELETE is idempotent (deleting same resource twice gives same result). Successful DELETE returns 200 OK or 204 No Content. Body optional. Should require authentication and authorization. Cannot be cached. Commonly used in REST APIs for resource removal.

Question 5

What is HEAD method used for?

Accepted Answer

HEAD returns headers only without body, like GET without response content. Use HEAD to: check if resource exists, get metadata (size, type, last-modified), test links, verify caching. HEAD is safe and cacheable. Useful for checking file size before downloading. Returns same headers as GET would return.

HTTP Methods Reference

GET

All Methods Summary

REST API Best Practices

Idempotent Methods