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HTML5
HTML5, or Hypertext Markup Language 5, is the fifth major revision of the markup language used to build web pages, published as a W3C Recommendation in 2014.
HTMS Chakri Naruebet
HTMS Chakri Naruebet (จักรีนฤเบศร) is the flagship and only aircraft carrier of the Royal Thai Navy, built in Spain on a Spanish design and commissioned in 1997.
Htmx
Htmx is a small JavaScript library, begun as intercooler.js by Carson Gross in 2013, that lets web pages issue AJAX requests and use WebSockets directly from HTML attributes.
HTPB
HTPB, or hydroxyl-terminated polybutadiene, is a liquid synthetic rubber used chiefly as the fuel-binder of composite solid rocket propellants and as the liner bonding propellant grains to motor cases.
HTR-10
The HTR-10 is a 10 MW thermal pebble-bed test reactor in Beijing, built by Tsinghua University, China's first high-temperature gas-cooled reactor, which reached criticality in 2000.
HTR-PM
The HTR-PM is a Chinese demonstration nuclear plant at Shidao Bay, Shandong, pairing two pebble-bed high-temperature gas-cooled reactors with one turbine; it reached commercial operation in 2023 as the world's first modular HTGR plant.
HTS magnet
An HTS magnet is a superconducting magnet made from high-temperature superconductor material, usually REBCO tape, operating at 20 to 30 K and central to compact fusion designs.
HTTP
HTTP, or Hypertext Transfer Protocol, is the stateless request/response protocol that underlies the Web, designed in the early 1990s and evolved through versions HTTP/1.1, HTTP/2, and HTTP/3.
HTTP 301
HTTP 301, "Moved Permanently," is an HTTP status code telling a client a resource has a new permanent URL; browsers follow it, and search engines update their indexes to the new address.
HTTP 303
HTTP 303 See Other is an HTTP status code telling the client to retrieve the response with a GET request from a different URI, commonly used after form submissions.
HTTP 308 Permanent Redirect
HTTP 308 Permanent Redirect is an HTTP status code telling clients a resource has permanently moved, without changing the request method, defined in RFC 9110.
HTTP 403
HTTP 403 Forbidden is an HTTP client error status code indicating the server understood the request but refuses it, unlike 401, where authentication may help.
HTTP 404
HTTP 404, Not Found, is a client-error status code in HTTP meaning the server did not find the requested resource or will not disclose it.
HTTP 406 Not Acceptable
HTTP 406 Not Acceptable is a 4xx client-error status code, defined in RFC 9110, returned when the request's Accept headers rule out every representation the server can provide.
HTTP 408 Request Timeout
HTTP 408 Request Timeout is a client error status code a server sends when the client's request does not arrive completely within the server's waiting time.
HTTP 417 Expectation Failed
HTTP 417 Expectation Failed is a client error status code meaning the expectation in a request's Expect header, typically 100-continue, could not be met by an inbound server.
HTTP 424 Failed Dependency
HTTP 424 Failed Dependency is a WebDAV client error status code meaning a method could not be performed because a dependent action failed, defined in RFC 4918.
HTTP 451
HTTP 451 Unavailable For Legal Reasons is an HTTP status code returned when legal demands, such as court orders or government blocklists, deny access to a resource.
HTTP 451 Unavailable For Legal Reasons
HTTP 451 Unavailable For Legal Reasons is an HTTP status code indicating a server is blocking a resource because of a legal demand, such as a court order.
HTTP 501 Not Implemented
HTTP 501 Not Implemented is an HTTP server error status code meaning the server does not support the functionality needed to fulfill the request, defined in RFC 9110.
HTTP 503 Service Unavailable
HTTP 503 Service Unavailable is an HTTP server error status code indicating temporary overload or maintenance, with an optional Retry-After header suggesting when clients should retry.
HTTP 504 Gateway Timeout
HTTP 504 Gateway Timeout is an HTTP status code defined in RFC 9110, sent when a gateway or proxy receives no timely response from an upstream server.
HTTP 505 HTTP Version Not Supported
HTTP 505 HTTP Version Not Supported is a server error status code meaning the server does not support the major HTTP version used in the request, defined in RFC 9110.
HTTP 507 Insufficient Storage
HTTP 507 Insufficient Storage is a 5xx server error status code meaning the server cannot store the representation needed to complete a request, defined by WebDAV's RFC 4918.
HTTP compression
HTTP compression is the lossless compression of HTTP message bodies such as HTML, CSS, and JavaScript, negotiated between server and client to make pages load faster.
HTTP cookie
An HTTP cookie, also called a web browser cookie, is a small piece of data a website stores in your browser to remember logins and preferences.
HTTP ETag
The HTTP ETag, or entity tag, is an HTTP response header that identifies a version of a resource, enabling efficient cache validation and preventing accidental overwrites.
HTTP flood
An HTTP flood is a Layer 7 denial-of-service attack in which a botnet sends high volumes of HTTP requests to exhaust a web server's resources and block legitimate users.
HTTP Live Streaming
HTTP Live Streaming (HLS) is an adaptive bitrate streaming protocol developed by Apple in 2009 that delivers video and audio over ordinary HTTP in short segments.
HTTP persistent connection
An HTTP persistent connection, also known as a keep-alive connection or HTTP connection reuse, stays open after a response so later requests reuse it instead of opening a new one.