website
As a website (contraction of the words Web and page ), Web document , website , webpage or short side of a document as part of an offer in the World Wide Web called that with a browser by specifying a uniform resource locator retrieved (URL) and a Web server available can be. In this context, an HTML page or an HTML document is also used.
history
The first website was written and published on November 13, 1990 by Tim Berners-Lee on a NeXT computer - one day after he and Robert Cailliau published a new concept for a global hypertext project.
construction
Websites mostly consist of structured text in which images and other multimedia elements can be integrated. The essential feature of websites is that they contain references, so-called hyperlinks , to other websites and together form the hypertext. Every document has at least one address ( URL ) that can be accessed in a web browser . Websites can have static (fixed) or dynamic content. Dynamic content is regenerated each time it is called, preferably based on the result of a database query . In addition, the same content can be presented in different ways, for example as a print version or a version for the screen.
Web pages are mostly loaded from the Internet or an intranet , but can also be stored on a local storage medium , for example a hard drive . The totality of the web pages of a website is a website , website , website , website or colloquially called homepage called.
reception
Web pages on a screen are perceived differently than printed text pages. English eye-tracking experiments, in which the reader's eye movements are followed, showed that most visitors to a website skim (scan) the text and first scan the top edge and then the left edge of the content area with their eyes. The result is an F-shaped area that most visitors look at. Visitors who come to a website via a search engine preferably look there for their search term ( keyword ). These facts result in special requirements for the web text .
Creation
The creation and design of websites is summarized under the term web design . The basic language for creation is the markup language HTML , whereby the uniform and rational formatting of several websites can be facilitated by formatting languages such as Cascading Style Sheets (CSS). Additional languages have been developed, especially for the creation of dynamic pages, with the help of which complex web pages can be created (see website ).
Dynamic websites
In contrast to static web pages, which technically represent an HTML document on the web server, web pages are often generated dynamically or actively at the moment of request. This is useful if a website should contain very current information such as stock market prices or weather forecasts. In this case, the web server executes a program that has been specifically developed in advance for this task. It carries the data z. B. from databases and creates the HTML document. This is then transferred from the web server to the browser and displayed to the user.
Another use case arises from the need to react to input from the user, such as B. entering a search term in a search engine. The search engine software creates a list of suitable links based on the search term and creates a website that conveniently presents this list to the user.
The ability to dynamically generate web pages based on user input and database content quickly made the web a universal platform for many types of applications. The advantages lie in the independence of operating systems and other properties of the clients . The only basic requirements are a network connection to the server and a web browser.
Any program that can be executed on the server system can be used to generate dynamic web pages. In order to simplify programming, however, standards such as the Common Gateway Interface (CGI) were introduced to make web applications independent of the type of web server. The majority of CGI applications were and are written in the Perl programming language . Technologies such as PHP , J2EE and .NET have developed due to the rapidly increasing need for very powerful servers to operate web applications .
Since the content of extensive websites is usually entered by several people, a content management system (CMS) is often used in such projects . More and more, mostly PHP and MySQL -based solutions in free software are pushing onto the market, which can also be used quickly by inexperienced programmers as long as they do not exceed a certain complexity.
Dynamically generated static web pages
With the standardization for XML and XSLT in December 2000 the W3C showed a way how "real" and thus static HTML documents can be generated dynamically, which can take on the complexity of the database extracts of a CMS or even these Outperform: Simple, content-restricted, but well-structured output data in XML are converted into valid, complex HTML by an adapted XSL transformer, which is then available as a static document on the web server.
The main advantage is the higher performance , because the host computer does not have to put together complex websites until requested and the server can therefore cope with higher visitor numbers. Another advantage is the greater flexibility in design. In contrast to conventional CMS, where database content is inserted into ready-made and relatively rigid HTML templates, a structured XML output document has a significant influence on the layout and user guidance of the HTML document generated from it. This enables the layman to produce long and coherent content using an XML editor and to present it in an easily readable form, for example as a web-friendly e-book , whereby a single "website" can consist of several screen pages that are "folded" using CSS can be conveniently paged through or accessed via menu navigation. It is also possible to design entire websites as graphic user interfaces with several elements that can be operated in parallel.
For a long time, the main obstacle to the broad use of these significantly expanded options with regard to display and data storage was Microsoft Internet Explorer , which, as a long-term market leader, only offers sufficient standard conformity with regard to CSS with Version 8, which appeared in 2009.
Separation of content, presentation and behavior
A technology mix of different techniques is used in the implementation of websites. The basic techniques here are HTML , CSS and often JavaScript . There are various ways of combining these techniques within an HTML document (website). The JavaScript code can e.g. B. can be placed directly "inline" in the HTML description. The “Script” tag from HTML can be used for this. Furthermore, direct connections with certain JavaScript functions can be set via HTML event handler attributes such as “onclick” or “ontouchstart”. Such an approach mixes logic for the description of the content, the design and the behavior. Due to a mixture, later changes to the behavior cannot be made without also taking content (HTML) and presentation (CSS) into account. In the case of separation, this can be adjusted and further developed separately. Furthermore, the HTML document is simplified and remains free of longer JavaScript areas and CSS definitions. The following separation should be achieved:
- HTML content: The HTML document should only keep the content to be displayed. The HTML tags used for this should be free of event handler attributes and inline JavaScript code. Styling attributes with CSS content should also not be used in the HTML markup.
- Visual representation: The visual representation of the content of the view should be defined in separate CSS files. The styles defined there are used by the rendering engine of the web browser when building the view. The separate definition of the visual representation also allows easier adaptation of the presentation for different output media. For example, a responsive web design can be implemented that automatically adapts to the technical conditions of the end device, such as B. the screen size. The integration of the CSS file in the HTML document should only take place via a "Link" tag in the header of the document. Older HTML tags for adapting visual representations, such as font or center, are no longer to be used and have been marked as out of date ("deprecated") with HTML5.
- Behavior: The client-side behavior of a website and the registration for input events should only take place in the JavaScript code. This code should be placed in separate JavaScript files. The JavaScript file is also integrated into the HTML document using the script tag. However, an external file is addressed with the src attribute. When integrating JavaScript files in an HTML document, the strategy of defining all script tags at the end of the HTML document has become the norm. The reason for this is the rendering behavior of web browsers. As soon as the web browser finds a script tag, the script is downloaded and executed. Only after this process does the actual rendering of the rest of the content of the HTML document continue. If the header of the HTML document already defines several scripts, the website will remain blocked until all scripts have been loaded. Alternatively, the async or defer attribute of HTML5 can be used for the script tag. However, the script files to be loaded must then not have any dependencies, since the exact sequence of loading is no longer defined.
If the described separation of content, behavior and presentation is taken into account, the techniques used for the implementation of websites are also divided into individual areas. There is no direct mixing. The strict separation increases the maintainability and adaptability of the document. This separation also enables easier division of tasks when realizing a web project.
Mobile website
Web links
- de.selfhtml.org - HTML reference
Individual evidence
- ^ Copy of the first website at w3.org
- ↑ Jakob Nielsen (2006): F-Shaped Pattern For Reading Web Content
- ↑ Jakob Nielsen (1997): How Users Read On the Web
- ↑ [1] , presentation on the maintainability of web applications