What is HTML

  HyperText Markup Language

The Authoring Language used to create Web Pages on the Internet
With HTTP Status Codes and their definitions
Updated: July 11, 2019
By: RSH Web Editorial Staff
blogs

HTML

A computer programming language devised to allow website creation. These websites can then be viewed by anyone on the Wold Wide Web. It is fairly easy to learn, And quite powerful in the creation of web sites. Web pages created with HTML are normally viewed in a web browser. They can include writing, links, pictures, and even sound and video. HTML is used to mark and describe each of these kinds of content so the web browser can display them correctly

HTML also defines the structure and layout of a Web document or web page by using a variety of tags and attributes. The correct structure for an HTML document starts with
<HTML> <HEAD> <BODY> and ends with </BODY></HTML>
All the information you would include in your Web page fits in between the <BODY> and </BODY> tags

HTML can be used to add meta information to a web-page

Meta information is usually not shown by web browsers and is data about the web page, e.g., the name of the person who created the page. Cascading Style Sheets (CSS) is used to style HTML elements while JavaScript is used to manipulate HTML elements and CSS styles

HTML Formatting Tags

There are hundreds of other tags used to format and layout the information in a Web page. Tags are also used to specify hypertext links. These allow Web developers to direct users to other Web pages with only a click of the mouse on either an image or words. For a more complete list of HTML tags, See the WC3 website

HTML (HyperText Markup Language)

Created by the World Wide Web Consortium (W3C). There are several versions of HTML. As of September 2018, the current standard of HTML is dubbed HTML 5 and is specifically at version 5.2

html

HTML4 vs. HTML5

The separation of concerns pattern is more rigorously enforced in HTML5 than it was in HTML4. With HTML5, the bold <b> and italicize <i> tags have been deprecated. For the paragraph tag, the align attribute has been completely removed from the HTML specification. For the purpose of backward-compatibility, web browsers will continue to support these deprecated HTML tags, but the changes to the HTML specification do demonstrate the desire of the community for HTML to return to its original purpose of describing the structure of content, while encouraging developers to use cascading style sheets for formatting purposes

HTML tag vs. element vs. attribute

The idea of using text to describe how text should be displayed might sound somewhat paradoxical, but it is not. This is the whole reason why HTML is known as a markup language. Using HTML, a document containing text is further marked up with additional text describing how the document should be displayed. To keep the markup part separate from the actual content of the HTML file, there is a special, distinguishing HTML syntax that is used. These special components are known as HTML tags. The tags can contain name-value pairs known as attributes, and a piece of content that is enclosed within a tag is referred to as an HTML element

What is well-formed HTML?

In order for a web browser to display an HTML page without error, it must be provided with well-formed HTML. To be well-formed, each HTML element must be contained within an Opening tag and a Closing tag
<p> </p>
<h1> </h1>
<div> </div>
Furthermore, any new tag opened within another tag must be closed before the containing tag is closed
Example would be:
<h1><p>Well Formed HTML</p></h1>
This is considered a well formed HTML because they start and end in the same order

HTML Syntax Standards

Another syntax rule is that HTML attributes should be enclosed within single or double quotes. There is often debate about which format is technically correct, but the World Wide Web Consortium asserts that both approaches are acceptable. The best advice for choosing between single and double quotes is to keep the usage consistent across all the documents. HTML style checkers can be used to enforce consistent use across pages. It should be noted that sometimes using a single quote is required, such as in an instance where an attributes value actually contains a double quote character. The reverse is true as well

"Single quote marks can be included within the attribute value when the value is delimited by double quote marks, and vice versa."

How to use and implement HTML

Because HTML is completely text-based, an HTML file can be edited simply by opening it up in a program such as Notepad++, Vi or Emacs. Any text editor can be used to create or edit an HTML file and, so long as the file is created with a .html extension, any web browser, such as Chrome or Firefox, will be capable of displaying the file as a web-page. For professional software developers, there are a variety of WYSIWYG editors to develop web pages. NetBeans, IntelliJ, Eclipse and Microsoft's Visual Studio provide WYSIWYG editors as either plug-ins or as standard components, making it incredibly easy to use and implement HTML

These WYSIWYG editors also provide HTML troubleshooting facilities, although modern web browsers often contain web developer plug-ins that will highlight problems with HTML pages, such as a missing end tag or syntax that does not create well-formed HTML. Chrome and Firefox both include HTML developer tools that allow for the immediate viewing of a web page's complete HTML file, along with the ability to edit HTML on the fly and immediately incorporate changes within the browser

The HTML Standard

HTML is a formal recommendation by the World Wide Web Consortium (W3C) and is generally adhered to by all major web browsers, including both desktop and mobile web browsers. HTML5 is the latest version of the specification


HTTP Status Codes

Reference database of HTTP Status Codes with their definitions and helpful code references

1xx: Information

100 Continue
Only a part of the request has been received by the server, but as long as it has not been rejected, the client should continue with the request

101 Switching Protocols
The server switches protocol

2xx: Successful

200 OK
The request is OK

201 Created
The request is complete, and a new resource is created

202 Accepted
The request is accepted for processing, but the processing is not complete

203 Non-authoritative Information
The information in the entity header is from a local or third-party copy, not from the original server

204 No Content
A status code and a header are given in the response, but there is no entity-body in the reply

205 Reset Content
The browser should clear the form used for this transaction for additional input

206 Partial Content
The server is returning partial data of the size requested. Used in response to a request specifying a Range header

3xx: Redirection

300 Multiple Choices
A link list. The user can select a link and go to that location. Maximum five addresses

301 Moved Permanently
The requested page has moved to a new url

302 Found
The requested page has moved temporarily to a new url

303 See Other
The requested page can be found under a different url

304 Not Modified
This is the response code to an If-Modified-Since or If-None-Match header, where the URL has not been modified since the specified date

305 Use Proxy
The requested URL must be accessed through the proxy mentioned in the Location header

306 Unused
This code was used in a previous version. It is no longer used, but the code is reserved

307 Temporary Redirect
The requested page has moved temporarily to a new url

4xx: Client Error

400 Bad Request
The server did not understand the request

401 Unauthorized
The requested page needs a username and a password

402 Payment Required
You can not use this code yet

403 Forbidden
Access is forbidden to the requested page

404 Not Found
The server can not find the requested page

405 Method Not Allowed
The method specified in the request is not allowed

406 Not Acceptable
The server can only generate a response that is not accepted by the client

407 Proxy Authentication Required
You must authenticate with a proxy server before this request can be served

408 Request Timeout
The request took longer than the server was prepared to wait

409 Conflict
The request could not be completed because of a conflict

410 Gone
The requested page is no longer available

411 Length Required
The "Content-Length" is not defined. The server will not accept the request without it

412 Precondition Failed
The pre condition given in the request evaluated to false by the server

413 Request Entity Too Large
The server will not accept the request, because the request entity is too large

414 Request-url Too Long
The server will not accept the request, because the url is too long. Occurs when you convert a "post" request to a "get" request with a long query information

415 Unsupported Media Type
The server will not accept the request, because the mediatype is not supported

416 Requested Range Not Satisfiable
The requested byte range is not available and is out of bounds

417 Expectation Failed
The expectation given in an Expect request-header field could not be met by this server

418 I'm a teapot
This code was defined in 1998 as one of the traditional IETF April Fools' jokes

421 Misdirected Request
The request was directed at a server that is not able to produce a response

422 Unprocessable Entity
The request was well-formed but was unable to be followed due to semantic errors

423 Locked
The resource that is being accessed is locked

424 Failed Dependency
The request failed because it depended on another request and that request failed

425 Too Early
Indicates that the server is unwilling to risk processing a request that might be replayed

426 Upgrade Required
The client should switch to a different protocol such as TLS/1.0, given in the Upgrade header field

428 Precondition Required
The origin server requires the request to be conditional. Intended to prevent the 'lost update' problem

429 Too Many Requests
The user has sent too many requests in a given amount of time. Intended for use with rate-limiting schemes

431 Request Header Fields Too Large
The server is unwilling to process the request because either an individual header field, or all the header fields collectively, are too large

451 Unavailable For Legal Reasons
A server operator has received a legal demand to deny access to a resource or to a set of resources that includes the requested resource

5xx: Server Error

500 Internal Server Error
The request was not completed. The server met an unexpected condition

501 Not Implemented
The request was not completed. The server did not support the functionality required

502 Bad Gateway
The request was not completed. The server received an invalid response from the upstream server

503 Service Unavailable
The request was not completed. The server is temporarily overloading or down

504 Gateway Timeout
The gateway has timed out.

505 HTTP Version Not Supported
The server does not support the "http protocol" version

506 Variant Also Negotiates
Transparent content negotiation for the request results in a circular reference

507 Insufficient Storage
The server is unable to store the representation needed to complete the request

508 Loop Detected
The server detected an infinite loop while processing the request

510 Not Extended
Further extensions to the request are required for the server to fulfil it

511 Network Authentication Required
The client needs to authenticate to gain network access. Intended for use by intercepting proxies used to control access to the network


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