HTTP/HTTPS
Definition
HTTP (Hypertext Transfer Protocol) is the foundation protocol of the World Wide Web, defining how messages are formatted and transmitted over the internet. HTTPS is HTTP over TLS, adding encryption and authentication.
HTTP is a request-response protocol: clients send requests, servers return responses. It is stateless by design (each request is independent).
HTTP Methods
| Method |
Purpose |
Idempotent |
Safe |
| GET |
Retrieve resource |
Yes |
Yes |
| POST |
Create resource |
No |
No |
| PUT |
Replace resource |
Yes |
No |
| PATCH |
Partial update |
No |
No |
| DELETE |
Delete resource |
Yes |
No |
| HEAD |
Get headers only |
Yes |
Yes |
| OPTIONS |
Supported methods |
Yes |
Yes |
HTTP Versions
| Version |
Year |
Key Features |
| HTTP/1.0 |
1996 |
Basic request-response |
| HTTP/1.1 |
1997 |
Persistent connections, pipelining, chunked encoding |
| HTTP/2 |
2015 |
Multiplexing, header compression (HPACK), binary framing |
| HTTP/3 |
2022 |
QUIC protocol (UDP), 0-RTT, improved congestion control |
HTTP Status Codes
| Category |
Codes |
Meaning |
| 1xx |
100-199 |
Informational |
| 2xx |
200-299 |
Success (200 OK, 201 Created) |
| 3xx |
300-399 |
Redirection (301 Moved, 302 Found, 304 Not Modified) |
| 4xx |
400-499 |
Client error (400 Bad Request, 401 Unauthorized, 403 Forbidden, 404 Not Found) |
| 5xx |
500-599 |
Server error (500 Internal, 502 Bad Gateway, 503 Service Unavailable) |
HTTP vs HTTPS
| Feature |
HTTP |
HTTPS |
| Port |
80 |
443 |
| Encryption |
None |
TLS encrypted |
| Authentication |
None |
Certificate-based |
| Performance |
Slightly faster |
TLS handshake overhead |
| SEO |
Lower ranking |
Google ranking boost |
| Adoption |
Deprecated |
Universal standard |
