HTML (HyperText Markup Language) is the language that gives a web page its structure. Every browser reads HTML and turns it into the page you see, using tags to mark what each piece of content is. A heading sits inside <h1> tags, a paragraph inside <p> tags, and a link inside <a> tags. The browser does the rest.
A good way to picture it is the skeleton and labelled boxes of a moving job. HTML decides that this box is the heading, that one is the main text, and this other one is an image, and it stacks them in order. It does not paint the walls or pick the furniture. That styling job belongs to CSS, which dresses the same structure in colours, fonts and spacing. The two split the work cleanly: HTML says what something is, CSS says how it should look, and that separation is what lets you redesign a whole site without rewriting the content.
HTML is also what makes the web connected. A hyperlink is just an HTML tag pointing at another address, and that single idea is what lets you jump from page to page across the entire internet. Search engines read your HTML too, so clean, well-labelled markup helps them understand what your page is about. The same goes for screen readers: when a heading is a real <h1> instead of a fat bit of text, a visually impaired visitor can hear the page’s outline and skip straight to the part they want. Good HTML is invisible to most people, but it quietly decides who can use your site and how well Google reads it.
At TopDevs we write lean, semantic HTML by hand, because clean structure is what makes a site fast, accessible and easy for Google to read.