Introduction to Web Fundamentals: HTML, CSS, and JavaScript
While Python is your primary tool for data science and AI, understanding the basics of web development—specifically HTML, CSS, and JavaScript—is crucial for presenting your findings, building interactive dashboards, and deploying web applications. This module introduces these foundational web technologies.
HTML: The Structure of the Web
HTML (HyperText Markup Language) is the standard markup language for documents designed to be displayed in a web browser. It defines the meaning and structure of web content. Think of it as the skeleton of a webpage.
HTML uses tags to define elements and structure content.
HTML documents are built using elements, which are typically defined by opening and closing tags. For example, <p> starts a paragraph, and </p> ends it. Content goes between these tags.
An HTML element consists of a start tag, content, and an end tag. Some elements, like images (<img>), are self-closing. Common tags include <h1> for main headings, <p> for paragraphs, <a> for links, <img> for images, and <div> for generic containers. Attributes within tags provide additional information, such as the src attribute for <img> tags to specify the image source.
To define the structure and content of a webpage.
CSS: Styling and Presentation
CSS (Cascading Style Sheets) is a style sheet language used for describing the presentation of a document written in a markup language like HTML. It controls how elements look on the screen, page, or in other media. CSS is responsible for the aesthetics—the colors, fonts, layout, and overall visual design.
CSS uses selectors to target HTML elements and apply styles.
CSS rules consist of a selector and a declaration block. The selector targets an HTML element (e.g., p for paragraphs, .my-class for elements with class 'my-class'), and the declaration block contains style properties and values (e.g., color: blue; font-size: 16px;).
Selectors can target elements by tag name, class, ID, attributes, and more. Properties like color, background-color, font-family, margin, padding, and display are used to control appearance. The 'cascading' nature means that styles can be inherited and overridden based on specificity and order, allowing for complex and organized styling.
Consider a simple HTML structure: <div><p>Hello World</p></div>. To style the paragraph with blue text and a larger font size, you'd use CSS. A CSS rule targeting the paragraph might look like this: p { color: blue; font-size: 20px; }. This rule selects all <p> elements and applies the specified styles. The color property sets the text color, and font-size adjusts the text size. This demonstrates how CSS rules connect to HTML elements to visually alter their appearance.
Text-based content
Library pages focus on text content
To control the visual presentation and styling of HTML elements.
JavaScript: Interactivity and Dynamic Behavior
JavaScript is a programming language that enables you to create dynamically updating content, control multimedia, animate images, and pretty much everything else on a webpage that isn't static. It adds interactivity and makes web pages come alive.
JavaScript manipulates the Document Object Model (DOM) to change content and behavior.
JavaScript code can be embedded directly into HTML or linked as external files. It interacts with the webpage by accessing and modifying HTML elements (the DOM), responding to user events (like clicks or scrolls), and fetching data.
The Document Object Model (DOM) is a programming interface for HTML and XML documents. It represents the page so that programs can change the document structure, style, and content. JavaScript can select elements, change their content, add or remove elements, and respond to events. For instance, a button click can trigger a JavaScript function to display a hidden message or update a chart.
While Python excels at backend logic and data processing, JavaScript is the primary language for frontend interactivity. Frameworks like React, Vue, and Angular, built on JavaScript, are commonly used for complex web applications.
To add interactivity and dynamic behavior.
Connecting Web Fundamentals to Python
Python web frameworks like Flask and Django allow you to build the backend of web applications. These frameworks serve HTML pages, which are then styled by CSS and made interactive by JavaScript. For data science and AI, you might use Python to generate data visualizations (e.g., with Matplotlib or Plotly) and then embed these into a web page using these frontend technologies.
| Technology | Primary Role | Analogy |
|---|---|---|
| HTML | Structure and Content | Skeleton of a building |
| CSS | Styling and Presentation | Paint, wallpaper, and interior design |
| JavaScript | Interactivity and Behavior | Electrical wiring and appliances |
Learning Resources
A comprehensive guide to the fundamental concepts of HTML, covering structure, elements, and attributes.
Learn the core concepts of CSS, including selectors, properties, and values, to style web pages.
An introduction to JavaScript, explaining its role in web development and basic syntax.
A hands-on curriculum covering HTML, CSS, and responsive design principles through interactive challenges.
A widely used resource for learning HTML with examples and interactive exercises.
Provides a thorough introduction to CSS, covering styling, layout, and advanced techniques.
A beginner-friendly tutorial for learning JavaScript, including syntax, DOM manipulation, and events.
An interactive course that teaches the fundamentals of HTML through practical coding exercises.
A video-based course that breaks down HTML and CSS concepts in an accessible way.
A comprehensive and modern tutorial covering JavaScript from basics to advanced topics, with clear explanations and examples.