HTML (HyperText Markup Language) is a markup language used to build and format web pages. HTML is an essential part of web development techniques and is used to define the structure and organization of web page content. Here are some of the main functions of HTML:

Determine the basic structure of the page:
HTML allows a page to be divided into structural elements such as <header>, <footer>, <nav>, <section>, <article>, and <aside>.

Inserting text and media:
You can use HTML to insert text using elements such as <p>, <h1>, <h2>, ... <h6>, as well as media such as images (<img>), video (<video>), and audio (<audio>) .

Create links:
HTML allows creating links using <a> to link to other pages or external resources.

Text and page formatting:
HTML provides text formatting elements such as <strong> for bold text and <em> for italic text. The page can also be formatted using basic formatting units.

Create forms:
You can use HTML to create interactive forms using elements such as <form>, <input>, <select>, <textarea>, and others.

Tables support:
HTML allows creating tables using <table>, <tr>, <td>, <th> to organize data into tables.

Integration with CSS and JavaScript:
HTML allows easy integration with CSS (Cascading Style Sheets) to define formatting and JavaScript to achieve interactivity and dynamism.

Define meta-data:
HTML can be used to provide meta information about a page such as title, description, and keywords.

HTML essentially cooperates with CSS to better format pages and with JavaScript to provide greater interactivity and dynamism.