Introduction to Web Services: HTML, XML and Web Technologies

Hello students, welcome to Kwickprep. You type a website address and a page appears in a second. Which technologies worked together to make that happen? Today we will learn what web services are, and how HTML gives structure while XML carries data. We will also see how web technologies fit together, and where these topics appear in your syllabus.

First, two words students often mix up. The internet is a worldwide network that connects millions of computers. The World Wide Web, or WWW, is a huge collection of web pages linked to each other, which we open using the internet. So the web is only one service that runs on the internet. Email and video calls are other services on the same internet.

In your syllabus, web services means the services and technologies that together make the web work. They include WWW, HTML, XML, HTTP, URLs, web browsers, web servers and web hosting. In software, a web service also means one program sending data to another program over the web. For example, a travel app does not run the railway system. It asks a railway data service over the web and shows you the live train status.

Now HTML, the language of web pages. HTML stands for HyperText Markup Language. Hypertext means text with links that take you to other pages. Markup means we mark each part of the page with tags, like a heading, a paragraph or a link. HTML tags are predefined, which means you can only use the tags HTML already has. The browser reads these tags and displays the page on your screen.

Here is a tiny HTML page. The html tag wraps the whole page, and the body tag holds what you see. The h1 tag makes a big heading, Kwickprep Results. The p tag makes a paragraph, Riya scored ninety two marks. Notice each opening tag has a closing tag with a slash. HTML tells the browser how the page is structured and shown, not what the data means.

Next, XML. XML stands for Extensible Markup Language. It is used to store and carry data between programs, not to design a page. Extensible means you can extend it, by inventing your own tags, like student or marks. XML is strict, so every tag must be closed and tags must be nested correctly, or the file is not valid.

Here is Riya's result in XML. The tags student, name, class and marks were made up by us, and they describe what each value means. The value ninety two sits inside the marks tag, so any program knows it is marks. This XML does not say anything about colour, size or layout. It only carries the data.

Board exams often ask the difference between HTML and XML. HTML is used to display data, while XML is used to store and carry data. HTML tags are predefined, while XML tags are defined by the user. In HTML some closing tags, like the p tag, can be left out, but in XML every tag must be closed. HTML tags are not case sensitive, but XML tags are, so capital Name and small name are different.

Pause and predict. A file has an opening tag marks in small letters, but the closing tag is Marks with a capital M. Would this be valid XML? No, because XML is case sensitive, so the closing tag does not match the opening tag. It is also not an HTML tag at all, because marks is a tag we invented.

A few more terms complete the picture. HTTP is the protocol, or set of rules, that browsers and servers use to send web pages, and HTTPS is its secure, encrypted form. A URL is the full address of a page on the web. A domain name is the easy name of a website, like cbse dot gov dot in, which DNS turns into a numeric IP address. A web browser, like Chrome or Firefox, is the app that requests and shows pages. A web server is a computer that stores websites and sends pages when asked.

Two more pairs of terms are easy to mix up. A web page is a single document. A website is a group of related pages under one domain name. Web hosting means renting space on a web server to keep your website's files. Because the server stays on the internet all day, people can open your website at any time.

Now let us see how these technologies fit together. You type a URL in the browser. DNS, the Domain Name System, finds the IP address of the web server for that name. The browser sends an HTTP or HTTPS request to that server. The web server, run by a hosting company, sends back the HTML page. The page may fetch extra data from a web service, in a format like XML or JSON. Finally, the browser reads the HTML and shows the finished page on your screen.

Where will you meet these topics in exams? Web services, like WWW, HTML, XML, HTTP and web hosting, are asked by name and meaning. HTML questions ask you to write and read a small page. And you are often asked how HTML and XML differ. So learn the meanings, and the HTML versus XML differences, well.

Here are questions that exams ask again and again. Write at least four differences between HTML and XML. Expand short forms like HTML, XML, HTTP, URL and WWW correctly. Define web hosting in one or two lines. And explain the difference between a website and a web page with an example.

Let us revise what we learned today. Web services are the technologies and services that make the web work, and programs can also share data through them. HTML shows data using predefined tags. XML stores and carries data using tags you define yourself. A URL, DNS, HTTP, a web server and a browser work together to show every page. For exams, learn the differences and the full forms well.