Topic Cluster
HTTP Fundamentals
Core HTTP primitives and baseline concepts every web engineer should know.
HTTP DELETE Method: Remove Resources
Learn how the HTTP DELETE method works, when to use it, and best practices for deleting resources in REST APIs.
HTTP HEAD Method
Learn how HTTP HEAD requests retrieve resource metadata (headers) without downloading the body. Useful for checking existence, size, and modification dates.
HTTP OPTIONS Method
Learn how HTTP OPTIONS requests discover server capabilities, supported methods, and handle CORS preflight checks for cross-origin requests.
HTTP PATCH Method
Learn how HTTP PATCH requests apply partial modifications to resources. Understand JSON Patch, merge patch formats, and when to use PATCH vs PUT.
HTTP PUT Method: Update Resources
Learn how the HTTP PUT method works, when to use PUT vs POST vs PATCH, and best practices for updating resources in REST APIs.
100 Continue
The server received the request headers and the client should proceed to send the body. Learn when and how to use 100 Continue for efficient large uploads.
101 Switching Protocols
The server is switching to a different protocol as requested by the client. Learn about WebSocket upgrades and protocol negotiation.
102 Processing
The server has accepted the request and is processing it, but no response is available yet. Learn about this WebDAV status code for long-running operations.
202 Accepted
The request was accepted for processing but not completed yet. Learn when to use 202 for asynchronous operations.
204 No Content
The request succeeded with no response body. Learn when to use 204 No Content for successful operations that don't return data.
300 Multiple Choices
The request has multiple possible responses. Learn when to use 300 Multiple Choices for content negotiation and alternative resource locations.
303 See Other
Redirect to a different resource using GET. Learn when to use 303 to prevent form resubmission and implement the Post-Redirect-Get pattern.
307 Temporary Redirect
Temporary redirect that preserves the HTTP method. Learn when to use 307 instead of 302 for method-sensitive redirects.
308 Permanent Redirect
Permanent redirect that preserves the HTTP method. Learn when to use 308 instead of 301 for method-sensitive permanent redirects.
402 Payment Required
Reserved for future use in digital payment systems. Learn about this experimental status code and modern payment verification alternatives.
426 Upgrade Required
The server refuses to perform the request using the current protocol and requires the client to upgrade to a different protocol.
HTTP 302 Found: Temporary Redirect
Learn what 302 redirect means, when to use temporary vs permanent redirects, and how 302 differs from 301, 307, and 308.
Accept Header
Learn how the Accept header tells servers which content types (JSON, HTML, XML) your client can handle. Master content negotiation and quality values.
Accept-Language Header
Learn how the Accept-Language header tells servers which languages your client prefers for localized content. Understand language tags and quality values.
Connection Header
Learn how the Connection header controls whether HTTP connections stay open (keep-alive) or close after each request. Optimize with persistent connections.
Content-Disposition Header
Learn how the Content-Disposition header controls whether content displays inline or downloads as an attachment. Set custom filenames for file downloads.
Content-Language Header
Learn how the Content-Language header specifies the natural language(s) of response content. Understand language tags and internationalization best practices.
Content-Length
Learn how Content-Length specifies the body size in bytes. Essential for progress indicators, connection management, and chunked transfer decisions.
Content-Location Header
Learn how Content-Location indicates an alternate URL for returned content. Useful for content negotiation and identifying canonical resource locations.
Date Header
Learn how the Date header specifies when the HTTP message was originated by the server. Understand date formats and its role in caching and logging.
Forwarded
Learn how the Forwarded header preserves original client information (IP, protocol, host) that would otherwise be lost when requests pass through proxies.
Host Header
Learn how the Host header specifies the target server domain name and port for HTTP requests. Essential for virtual hosting and routing on shared servers.
Location
Learn how the Location header specifies redirect URLs or the location of newly created resources. Essential for 201, 301, 302, and other redirect responses.
Referer Header
Learn how the Referer header tells servers which page led to the current request. Understand its use in analytics, security, and privacy implications.
Refresh Header
Learn how the Refresh header instructs browsers to reload or redirect after a delay. Understand its use cases, limitations, and better alternatives.
Retry-After
Learn how the Retry-After header tells clients how long to wait before retrying a request. Understand its use with 503, 429, and 301 status codes.
Sec-WebSocket-Accept
Learn how the Sec-WebSocket-Accept header indicates server acceptance of a WebSocket connection upgrade. Understand the handshake process and key validation.
Sec-WebSocket-Key
Learn how the Sec-WebSocket-Key header provides a random key for WebSocket handshake validation. Understand the upgrade process and security implications.
Transfer-Encoding Header
Learn how the Transfer-Encoding header specifies encoding formats like chunked transfer for streaming responses when content length is unknown beforehand.
Upgrade Header
Learn how the Upgrade header requests protocol upgrades to WebSocket, HTTP/2, or other protocols on the same TCP connection. Understand upgrade negotiation.
User-Agent Header
Learn how the User-Agent header identifies the client software, browser, or application making HTTP requests. Understand user agent strings and best practices.
Via Header
Learn how the Via header tracks the path of HTTP requests through proxies and gateways. Debug routing issues and understand your network infrastructure.
Warning Header
Learn about the deprecated Warning header that provided additional status information about message transformations. Understand why it was removed from HTTP.
X-Forwarded-For
Learn how X-Forwarded-For identifies the original client IP when requests pass through proxies or load balancers. Essential for logging and security.
X-RateLimit Headers
Learn how X-RateLimit headers inform API clients about rate limits, remaining requests, and reset times. Implement proper rate limiting in your applications.
Domain
Learn how the Domain cookie attribute controls which domains can access cookies. Understand subdomain sharing, security implications, and restrictions.
Expires
Learn how the Expires cookie attribute sets an absolute expiration date. Understand date formats, timezone handling, and when to use Expires vs Max-Age.
Max-Age
Learn how the Max-Age cookie attribute sets expiration in seconds from now. Understand why Max-Age is preferred over Expires for reliable lifetime control.
Path
Learn how the Path cookie attribute restricts which URL paths can receive cookies. Understand path matching rules and how to scope cookies to specific routes.
HTTP Sessions and State Management Explained
Learn how to manage user state and sessions in stateless HTTP applications using cookies, tokens, and server-side storage.
HTTP Status Codes: A Complete Reference Guide
Learn how HTTP status code classes (1xx-5xx) work and when to use each code. Master informational, success, redirect, client error, and server error responses.
Request and Response Lifecycle
Learn how HTTP requests travel from browser to server and back. Understand DNS resolution, TCP connections, request/response flow, and the complete lifecycle.
HTTP Cookie
Learn what HTTP cookies are and how browsers store small data pieces for websites. Understand cookie attributes, security, and session management.
HTTP Header
Learn what HTTP headers are and how they provide metadata about requests and responses. Understand common headers like Content-Type and Authorization.
HTTP Method
Learn what HTTP methods are and how they define actions on resources. Understand GET, POST, PUT, DELETE, PATCH, and other methods with examples.
HTTP Payload
Learn what HTTP payload means and how message bodies carry data in requests and responses. Understand JSON, form data, and binary payloads.
HTTP Request
Learn what an HTTP request is and how clients send messages to servers. Understand request structure, methods, headers, and body components.
HTTP Response
Learn what an HTTP response is and how servers reply to client requests. Understand response structure, status codes, headers, and body content.
HTTP Session
Learn what HTTP sessions are and how they maintain state across stateless HTTP requests. Understand session cookies, tokens, and server-side storage.
HTTP Status Code
Learn what HTTP status codes are and how they indicate request results. Understand 1xx, 2xx, 3xx, 4xx, and 5xx code classes with common examples.
Idempotent
Learn what idempotent means in HTTP. Understand why GET, PUT, and DELETE are idempotent, why POST is not, and how idempotency affects API design.
More Topic Clusters
HTTP Performance
Caching, compression, connection behavior, and practical latency optimization topics.
HTTP Troubleshooting
Error diagnosis, status code debugging, and production-safe HTTP troubleshooting workflows.
HTTP Security
Security headers, cookie hardening, CORS policy design, and defensive API behavior.
HTTP Authentication
Auth flows, authorization semantics, credentials handling, and access control patterns.