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Web technologies—HTML documents

The Web platform is built upon the internet platform. These platforms are defined by program protocols. The web platform is defined by local browser/web server network technology, built upon a specialised set of data handling protocols compliant with Internet protocols.

Web browsers have engines that can read HTML documents, interface and interact with users through web page windows and communicate with web servers.

Web servers interact with web browser apps and can read various script types embedded in documents the browsers send to them. Web sites consist of one or more web pages uploaded and stored on web servers. Web browsers may request these pages invoking the server to prepare and send them to the requesting browser.

The browser will save them to a local cache so for the duration of that user session, or until the browser cache is cleaned out, it only needs to look locally every time the user requests it.

For the user to make changes, they need to edit the HTML tags, scripts or content in a text editor, because browsers are not designed for web page editing. Any changes made must be saved on the server. They may not show up in the browser immediately because the browser is pulling the page from its’ local cache, rather than the server. To overcome this, all browsers have a refresh option a user can invoke. This action will cause the browser to request the latest page from the server where the browser will then update its cached version. The whole design idea is to reduce internet traffic and server time.

Web pages are built upon HTML and its’ interaction with JavaScript. Other types of script such as PHP may also be present in a page, however browsers ignore those scripts as they are not intended for browsers. A server will read these scripts and invoke them as part of preparing a page to be sent to a browser.

HTML presents instructions enclosed in left and right chevron characters “<, >”. Usually a starting tag, some content and an end tag such as “<p> some text </p>”. There are some exceptions to the end tags that will be covered in “Student Notes”.

The browser interprets these tags and knows what to do. They are essentially instructions for the browser. A web server will ignore them.

Each HTML page is a .html document. A navigation menu must be embedded in each of them if they are to link to each other to form a multipage website.

CSS is an elaboration of the HTML style instructions. It allows style instructions to be contained in their own document that a HTML document can be linked to. Style instructions deal with page layout, positioning, margins, container padding, colours, tones, textures, fonts, transparency and everything to do with page and text styling and layout.

JavaScript can be declared locally on a page, or it too can be written as an independent document that a HTML document can link to. Its’ primary function is to provide extended functionality beyond what is possible through the HTML DOM (Document object model). Again JavaScript can only be read by browsers—a server will ignore JavaScript.

SEO is Search Engine Optimisation. Many websites are designed as marketing tools. When a search for information, a product or cause is invoked that is right up your alley, you hope your site will be found at, or near the top of the list of results. SEO increases your chances of this. There are many guides out there on things that can be done to improve your sites SEO. SEO is implemented through development design, not code.

Brief summary: There are three components to a website; form (aesthetics), function and SEO. According to popular principles of design, form follows function, meaning if you have to compromise between function and form, function should take priority. The HTML DOM provided some functionality and aesthetics, while JavaScript and other scripts provide extended functionality. CSS provides extended styling (aesthetics), while SEO is achieved by way of system design. Having CSS documents independent of HTML pages allows them to be shared by many HTML pages through links, reducing duplication.

Student Notes: Originally some HTML tags did not have closing tags. This introduced some conflict with evolving standards, so optional closing tags were introduced to meet the new standards. However for reasons of backward compatibility they remained optional as far as functionality was concerned. One such example is the br (line break) tag. To conform to newer standards developers are encouraged to write the tag as “<br />”.

(CC BY) Gavin Lardner 2018

 

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