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 websites. 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
All the information you would include in your Web page fits in between the
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.
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.
Following are some of the major characteristics that distinguish HTML5 from HTML4.
The syntax in HTML5 is extremely clear and simple as compared to HTML4. One example of this is the
<!DOCTYPE> element. In HTML4, the
<!DOCTYPE> declaration was too messy and lengthy and used to refer an external source. However, in HTML5,
<!DOCTYPE> element has been made extremely simple. For instance, a mere
<!DOCTYPE html> is enough to specify the document type.
HTML5 contains built in support for integrated multimedia files into a web page via video and audio tags. Previously, in HTML4, the multimedia content was integrated in web pages via third party plugins such as Silverlight and flash.
Previously in HTML4, it was an extremely cumbersome task to get the geographical locations of the visitors visiting the site. It was even difficult when the website was accessed through mobile devices. On the other hand, in HTML5, it is extremely easy to get the user location. HTML5’s JS GeoLocation can be leveraged to identify the location of the user accessing the website.
In HTML4, the communication between the client and server was done through streaming and long polling, since there are no web sockets available in HTML4. On the contrary, HTML5 contains web sockets that allow full duplex communication between clients and servers.
As aforementioned, HTML4 is an established standard for developing browser applications and has been in use for more than 10 years. For this reason, HTML4 is compatible with almost all web-browsers. On the other hand, HTML5 is still in the process of evolution and the currently available tags are being modified and also new tags are being added. Therefore, HTML5 lags behind HTML4 in terms of compatibility with the browsers.
Many HTML4 tags have been removed from HTML5 or their functionality has been changed. Following are a few of the tags that are removed from HTML5 or have different functionality in HTML5 as compared to HTML4.
HTML4 contained an
<applet> tag that was used for displaying applets. With HTML5, this applet tag has been removed. In order to display those applet type items, a new
<object> tag has been introduced in HTML5.
HTML4 contains a
<acronym> tag that was used for displaying abbreviation’s. With HTML5, this tag has been removed. A new
<abbr> tag has been added in HTML5.
<hr> tag was used to draw a line in HTML4 and all the previous versions of HTML. With HTML5, the functionality of this tag has been changed. It is used for defining a thematic break in the web page.
In HTML4 and previous versions, the
<a> tag was used as an anchor as well as for referring to a link. With HTML5, the
<a> tag is used only as a hyperlink. But if the href tag is removed from the
<a> tag, the
<a> tag can be used as a placeholder for other links.
Following are some of the attributes that have been changed with HTML5.
With HTML5, the
<table> tag can only have one attribute: the Border attribute. And the value of this attribute can only be zero or one. Previously, the
<table> tag had many attributes.
In the previous versions of HTML, the
<meta> tag did not have the char set attribute that defines the standard character encoding for the page. This attribute has been added in HTML5.
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.
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
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.
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."
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. If the file is created with a .html extension, any web browser, such as Chrome, Edge, 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.
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.
Reference database of HTTP Status Codes with their definitions and helpful code references.
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
The request is OK
The request is complete, and a new resource is created
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
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
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
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
400 Bad Request
The server did not understand the request
The requested page needs a username and a password
402 Payment Required
You can not use this code yet
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
The request could not be completed because of a conflict
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 precondition 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 media-type 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
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
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 fulfill 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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