CS50x 2026 - Lecture 8 - HTML, CSS, JavaScript | CS50

This CS50 lecture transitions to web app development, explaining how the internet functions and introducing HTML, CSS, and JavaScript. It details the internet's evolution from ARPANET to today's global network, emphasizing the role of routers and data packets using TCP/IP protocol. The lecture demystifies IP addresses, port numbers, and DNS servers, clarifying how devices communicate and translate domain names. HTTP and HTTPS are explored, revealing the structure of URLs and the messages exchanged between browsers and servers, including status codes like 200 OK, 301 Moved Permanently, and 404 Not Found. The lecture also covers HTML tags, CSS for styling, and JavaScript for dynamic content, demonstrating how these technologies combine to create interactive web experiences.

Outlines

Part 1: Introduction, Internet Fundamentals

Part 2: Networking Protocols, Addressing

Part 3: HTTP, Web Communication

Part 4: HTML Structure, Content

Part 5: CSS Styling, Frameworks

Part 6: JavaScript, Interactivity

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CS50x 2026 - Lecture 8 - HTML, CSS, JavaScript

CS50

Part 1: Introduction, Internet Fundamentals

Introduction to CS50 Week 8: Transitioning to Web and Mobile App Development

The Internet's Evolution: From ARPANET to Global Interconnection via Routers

Part 2: Networking Protocols, Addressing

TCP/IP Protocols: Ensuring Unique Addresses and Reliable Data Delivery

TCP and Port Numbers: Identifying Services and Guaranteeing Data Delivery

DNS and DHCP: Simplifying Internet Access with Domain Names and Automatic IP Configuration

Part 3: HTTP, Web Communication

HTTP Protocol: Requesting and Receiving Web Pages, Status Codes, and Redirection Examples

Browser Developer Tools: Inspecting Network Activity and Manipulating Website Elements

Part 4: HTML Structure, Content

HTML Fundamentals: Tags, Attributes, and Building a Simple Web Page

HTML Tags for Paragraphs, Headings, Lists, Tables, Images, and Videos

Hyperlinks and URLs: Connecting Web Pages and Passing Data via HTTP Parameters

Building a Search Engine Front-End and Validating Input with Regular Expressions

Part 5: CSS Styling, Frameworks

Validating HTML and Introducing CSS: Styling Web Pages with Properties and Selectors

CSS Classes and Frameworks: Reusing Styles and Leveraging Bootstrap for Enhanced Aesthetics

Advanced CSS Techniques: Pseudo-Selectors, Unique IDs, and JavaScript Integration

Part 6: JavaScript, Interactivity

JavaScript Fundamentals: Events, DOM Manipulation, and Dynamic Web Page Updates

CS50x 2026 - Lecture 8 - HTML, CSS, JavaScript

CS50

Part 1: Introduction, Internet Fundamentals

00:00Introduction to CS50 Week 8: Transitioning to Web and Mobile App Development

Introduction to CS50 Week 8: Transitioning to Web and Mobile App Development

00:44The Internet's Evolution: From ARPANET to Global Interconnection via Routers

The Internet's Evolution: From ARPANET to Global Interconnection via Routers

Part 2: Networking Protocols, Addressing

03:31TCP/IP Protocols: Ensuring Unique Addresses and Reliable Data Delivery

TCP/IP Protocols: Ensuring Unique Addresses and Reliable Data Delivery

06:17TCP and Port Numbers: Identifying Services and Guaranteeing Data Delivery

TCP and Port Numbers: Identifying Services and Guaranteeing Data Delivery

16:20DNS and DHCP: Simplifying Internet Access with Domain Names and Automatic IP Configuration

DNS and DHCP: Simplifying Internet Access with Domain Names and Automatic IP Configuration

Part 3: HTTP, Web Communication

22:22HTTP Protocol: Requesting and Receiving Web Pages, Status Codes, and Redirection Examples

HTTP Protocol: Requesting and Receiving Web Pages, Status Codes, and Redirection Examples

35:26Browser Developer Tools: Inspecting Network Activity and Manipulating Website Elements

Browser Developer Tools: Inspecting Network Activity and Manipulating Website Elements

Part 4: HTML Structure, Content

42:22HTML Fundamentals: Tags, Attributes, and Building a Simple Web Page

HTML Fundamentals: Tags, Attributes, and Building a Simple Web Page

52:25HTML Tags for Paragraphs, Headings, Lists, Tables, Images, and Videos

HTML Tags for Paragraphs, Headings, Lists, Tables, Images, and Videos

1:07:21Hyperlinks and URLs: Connecting Web Pages and Passing Data via HTTP Parameters

Hyperlinks and URLs: Connecting Web Pages and Passing Data via HTTP Parameters

1:15:15Building a Search Engine Front-End and Validating Input with Regular Expressions

Building a Search Engine Front-End and Validating Input with Regular Expressions

Part 5: CSS Styling, Frameworks

1:28:37Validating HTML and Introducing CSS: Styling Web Pages with Properties and Selectors

Validating HTML and Introducing CSS: Styling Web Pages with Properties and Selectors

1:35:56CSS Classes and Frameworks: Reusing Styles and Leveraging Bootstrap for Enhanced Aesthetics

CSS Classes and Frameworks: Reusing Styles and Leveraging Bootstrap for Enhanced Aesthetics

1:47:21Advanced CSS Techniques: Pseudo-Selectors, Unique IDs, and JavaScript Integration

Advanced CSS Techniques: Pseudo-Selectors, Unique IDs, and JavaScript Integration

Part 6: JavaScript, Interactivity

1:53:40JavaScript Fundamentals: Events, DOM Manipulation, and Dynamic Web Page Updates

JavaScript Fundamentals: Events, DOM Manipulation, and Dynamic Web Page Updates