What is HTML?
What HTML is, and how tags and elements describe the content of a page.
Every webpage you have ever visited — Google, Wikipedia, YouTube — is built from the same foundation: a plain text file full of angle brackets. Before any colors appear or any button works, the browser reads this file to find out what is on the page. That file is written in HTML.
HTML stands for HyperText Markup Language. It has exactly one job: describe content. Not how it looks — that is CSS, which you will meet later. Not how it behaves — that is JavaScript. HTML just says what each piece of content is: this is a heading, this is a paragraph, this is a link.
You describe content by wrapping it in tags. A tag is a keyword between angle brackets, like <p>. Most content is wrapped in a pair of tags:
<p>Hello, world!</p>Three parts are at play here:
<p>— the opening tag (pmeans paragraph)Hello, world!— the content inside</p>— the closing tag; the/slash means "this is where it ends"
An opening tag, its content, and its closing tag together form one element. So <p>Hello, world!</p> is a paragraph element. "Element" is the word you will use most in this course — it means one complete piece of content described by tags.
You already know more tags than you think — here are the ones you will use constantly:
<h1>The biggest heading</h1>
<h2>A smaller sub-heading</h2>
<p>A paragraph of body text.</p>
<a>a link</a>
<button>a clickable button</button><h1>…<h6>— headings, from largest (h1) to smallest (h6)<p>— a paragraph of text<a>— a link (you'll learn how to point it somewhere in Module 2)<button>— a button
Notice you did not tell the browser what size or color to make anything. HTML only names the content. The browser applies plain default styling, and later you will take full control with CSS.
What text appears on the page?
<h1>My Blog</h1>
<p>Welcome to my first website.</p>- AMy Blog Welcome to my first website.
- Bh1 My Blog p Welcome
- CMy Blog only
- DNothing — this needs CSS
Elements can live inside other elements. This is called nesting, and it is how every real page is built:
<p>Never share your <strong>password</strong> with anyone.</p>Here a <strong> element (which marks important text) is nested inside a <p> element. The golden rule of nesting: close tags in the reverse order you opened them — innermost first.
<!-- ✅ Correct: strong closes before p -->
<p>Text <strong>bold</strong> more text</p>
<!-- ❌ Wrong: tags overlap instead of nesting -->
<p>Text <strong>bold</p></strong>Think of it like boxes inside boxes: you cannot close the outer box until the inner box is sealed.
Which line is correctly nested?
- A<h1>Welcome <em>home</h1></em>
- B<h1>Welcome <em>home</em></h1>
- C<h1><em>Welcome home</h1>
- D<em><h1>Welcome home</em>
So where does HTML end and the rest of the web begin? A finished web page is usually three languages working together:
- HTML — the content and structure (headings, text, images, buttons). The skeleton.
- CSS — the presentation (colors, fonts, spacing, layout). The skin and clothing.
- JavaScript — the behavior (what happens when you click, type, or scroll). The muscles.
You are starting with HTML because nothing else can exist without it. There is no color to style and no button to click until the content exists first. Master HTML and the rest has something to attach to.
Complete this paragraph element by writing its closing tag:
<p>Learning web development___- HTML describes the content and meaning of a page — not its colors or behavior
- A tag is a keyword in angle brackets, like
<p>; most come in an opening/closing pair (<p>…</p>) - An opening tag, its content, and its closing tag together form one element
- Elements can be nested inside each other — always close the innermost one first
- A full web page combines HTML (structure), CSS (style), and JavaScript (behavior)
Next up: the extra information you can attach to tags — attributes — and the handful of tags that break the opening/closing rule.