Http Glossary

Browse 50 http terms defined in plain English, from the cultural dictionary of computing.

50 Http Terms

404
404 is the HTTP status code that means Not Found, returned by a web server when the requested resource does not exist at the specified URL. It is one of the...
404 Error Page
404 Error Page is the web page displayed to users when they attempt to access a URL that does not exist on a server, corresponding to the HTTP 404 Not Found...
API Endpoint
A specific network path or callable interface exposed by an API to perform an operation or access a resource. Endpoints are usually defined by a route plus...
API Rate Limit Header
HTTP response headers that inform API consumers about rate limit status: X-RateLimit-Limit (max requests per window), X-RateLimit-Remaining (requests left),...
Bad Gateway
Often used casually to refer to 502 errors or to the general situation where a proxy or gateway cannot get a valid response from an upstream service. In ops...
Cache Control
The policies and directives that determine whether and how a response may be cached, revalidated, or shared by browsers, CDNs, or proxies. In HTTP, cache...
Cache Proxy
A proxy that stores reusable responses and serves future matching requests from cache instead of always forwarding them upstream. Cache proxies are common in...
Content Encoding
The representation or transformation applied to response content, often indicated in protocols like HTTP to show compression or alternate encodings such as...
Content Negotiation
An HTTP mechanism where the client and server agree on the best representation of a resource. The client sends Accept headers (Accept: application/json,...
Content Type
A label describing the media type of data, such as `application/json`, `text/html`, or `image/png`, so systems know how to parse or handle it. Correct content...
Cookie
Cookie is a small piece of data that a web server sends to a user's browser, which stores it and sends it back with subsequent requests to the same server....
CORS
CORS, or Cross-Origin Resource Sharing, is a browser security mechanism that controls how web pages from one domain can request resources from a different...
CORS Origin
The scheme + hostname + port combination that identifies where a web request originates from. CORS (Cross-Origin Resource Sharing) checks prevent JavaScript on...
CORS Preflight
An automatic OPTIONS request sent by the browser before a cross-origin request to check whether the server allows it. Triggered by non-simple methods (PUT,...
cURL
A command-line tool and library for making network requests across many protocols, especially HTTP APIs.
Error 500
A casual reference to internal server errors, usually standing in for generic backend failure from a user's perspective. In engineering slang, '500' is often...
ETag
An HTTP response header containing a unique identifier (hash or version) for a specific version of a resource. Clients can send If-None-Match with the ETag on...
Fetch API
The modern browser API for making HTTP requests, replacing the older XMLHttpRequest. Returns Promises, supports streaming responses, and integrates with...
HTTP Method Tampering
A technique that abuses alternate or unexpected HTTP methods such as PUT, DELETE, or HEAD to bypass filters, reach hidden functionality, or trigger unsafe...
Idempotent Request
An HTTP request that produces the same result regardless of how many times it's executed. GET, PUT, DELETE, and HEAD are idempotent by design. POST is not --...
JSON API
An application programming interface that sends and receives data encoded as JSON, typically over HTTP. In practice the term often implies REST-style endpoints...
Koa
A minimalist Node.js web framework created by the same team behind Express, designed around async/await and a middleware stack that uses a cascading...
Long Polling
A technique where the client sends an HTTP request and the server holds it open until new data is available (or a timeout expires), then responds. The client...
Mitmproxy
An interactive proxy used to inspect, modify, and debug HTTP and related traffic in transit.
Negotiation
The process by which two communicating parties agree on parameters for their exchange — in HTTP, content negotiation uses `Accept`, `Accept-Language`, and...
Network Protocol
A formal specification of rules governing the format, sequencing, and error handling of data exchanged between networked systems — examples span every layer...
Port 80
The well-known TCP port traditionally used for unencrypted HTTP web traffic. From a security perspective, port 80 is often associated with redirecting users to...
Query Parameter
A key-value pair appended to a URL after the ? character (e.g., ?page=2&sort=name) used to pass data to a server in an HTTP GET request. Multiple parameters...
Rack
A Ruby web server interface specification that defines a minimal contract: an application is any object that responds to call(env) and returns a [status,...
Rails Router
The component in Ruby on Rails (defined in config/routes.rb) that maps incoming HTTP request URLs and methods to controller actions. It supports RESTful...
Ready State
A property (readyState) on browser objects like XMLHttpRequest and Document that indicates the current phase of a lifecycle — for XHR: 0 (UNSENT) through 4...
Request
A message sent from a client to a server asking it to perform an action — in HTTP, composed of a method (GET, POST, PUT, DELETE, etc.), a URL, headers, and an...
Request Handler
A function or method that receives an incoming HTTP request, executes the business logic for that endpoint (reading/writing data, calling services, validating...
Request-Response
A communication pattern in which a client sends a single request and synchronously waits for a single response from the server, forming a paired exchange. HTTP...
Response
A message sent from a server back to a client in answer to a request — in HTTP, composed of a status code (200, 404, 500, etc.), headers (Content-Type,...
REST API
An API that follows REST (Representational State Transfer) principles: resources are identified by URIs, manipulated via standard HTTP methods (GET, POST, PUT,...
Route
A mapping between a URL pattern (and optionally an HTTP method) and the handler function that should process matching requests. In frontend SPA frameworks,...
Route Handler
The function or method that executes when an incoming request matches a defined route. In Express it's the callback passed to app.get(); in Next.js App Router,...
Route Middleware
A function that intercepts an HTTP request before (or after) it reaches the route handler, performing cross-cutting concerns like authentication, logging, rate...
Security Headers
HTTP response headers that instruct browsers to enable security features. Key headers: Content-Security-Policy (XSS prevention), Strict-Transport-Security...
Server-Sent Events
A simple HTTP-based protocol for one-way server-to-client streaming. The server sends text events over a long-lived HTTP connection using the text/event-stream...
Short Polling
A client-side technique where the browser or application repeatedly sends HTTP requests to the server at fixed intervals (e.g., every 2 seconds) to check for...
Stale-While-Revalidate
A caching strategy (HTTP header and React Query/SWR pattern) that immediately returns stale cached data while simultaneously fetching a fresh version in the...
Upload
The transfer of data from a local client to a remote server, typically via HTTP multipart form data, FTP, or a cloud storage API. In web applications, uploads...
URL
Uniform Resource Locator — a specific type of URI that includes both the scheme (protocol) and the network location needed to retrieve a resource, such as...
URL Router
The component of a web framework or server that matches an incoming request's URL path (and often its HTTP method) against a set of registered route patterns...
User Agent
An HTTP header string that identifies the client software making a request, traditionally including the browser name, version, rendering engine, and operating...
Web API
An interface exposed over HTTP (typically REST, GraphQL, or gRPC-Web) that allows client applications to read and write server-side data and trigger...
Web Framework
A structured library or platform that provides conventions, routing, middleware, templating, and tooling for building web applications — server-side examples...
Web Server
Software (such as Nginx, Apache, or Caddy) that listens for incoming HTTP/HTTPS requests and responds by serving static files, proxying requests to application...

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