1.1 Understanding File Extensions1.1.1 Exercise 1: Add a New File with the txt Extension, and Then Change It to the Html Extension1.2 Opening a File with the Html Extension in Your Browser1.3 Editing a File Using Notepad1.4 Making Our index.html File Look Better1.4.1 Exercise 2: Adding Your First Tags1.5 How Does the Browser Know How to Display Annotated Text?1.5.1 What Is Whitespace?1.5.2 Exercise 3: How Does the Browser Deal with Whitespace in html Files?1.5.3 Whitespace Collapsing in HTML1.5.3.1 What Is ?1.5.3.2 HTML Elements1.6 Heading Tags in HTML1.7 HTML Attributes1.7.1 The Style Attribute in HTML1.7.1.1 Exercise 4: Practice Using the Style Attribute1.8 HTML Is for Structure and CSS Is for Display1.9 Multiple Property-Value CSS Pairs in the Style Attribute1.10 Block vs. Inline Elements1.11 Making Block Elements Inline and Vice-versa1.12 Using External Style Sheets in HTML Pages1.12.1 HTML DOCTYPE and Metadata1.12.2 Can Browsers Work Without DOCTYPE and Metadata?1.13 Using devtools1.13.1 Testing If the External Stylesheet Is Properly Linked1.13.2 The Anatomy of a CSS Declaration1.14 Moving Inline Styles to an External Stylesheet File1.14.1 Moving the h1 Styles to an External Stylesheet1.14.2 Moving the p Styles to an External Stylesheet1.14.3 Moving the Span Styles to an External Stylesheet1.15 CSS Specificity1.16 CSS Class Selectors and CSS id Selectors1.17 Adding an Interactive Button with the Help of JavaScript1.18 Using the Button HTML Element and the Onclick Attribute to Add Interactivity with JS1.19 How Browsers Work with Web Pages1.20 Conclusion