In Chapter 3, Defining Data Models, we learned about different types of data, including structured, semi-structured, and unstructured. In this section, we are going to discuss more semi-structured data. The World Wide Web (WWW) is the largest information source today. If we have to classify the data model behind the web, we can say it belongs to the semi-structured data model. Most of the semi-structured data refer to tree-structure data.
Let's take the example of a web page:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Page Title</title>
</head>
<body>
<h1>This is a Heading</h1>
<p>This is a paragraph.</p>
<ul>
<li>List Item 1</li>
<li>List Item 2</li>
<li>List Item 3</li>
</ul>
<footer><center>Copyright...
