HTML is the language used to show webpages in a browser.
When you go to a website, your browser is requesting a page from a server and the server serves the page pack to the browser.
Now, how does the browser know how to structure the page? Where do paragraphs start, what words to make bold, headers, lists and all that fancy stuff?
That's where HTML comes in. HTML stands for Hyper Text Markup Language. HTML is what servers use to structure the web page using tags, so the browser understands what to do with each piece of text.
<h1>What in the world is HTML?</h1> <p>This is <b>HTML</b>.</p>
Take a look at this example. We're using three HTML tags here. Each one starts with
<tag> and ends with
</tag>. We have
<h1> which tells us that this piece of text is a heading, so the browser will make it nice and big. The
<b> tag will make the text in between bold. And the paragraph tag starts a new paragraph.
You can take a look at the HTML of any website by right-clicking in the browser and selecting "View page source".