HTML stands for Hypertext Markup Language.
This is usually called hypertext because in HTML an ordinary text can function differently, we can make it a link that can move from one page to another just by clicking the text. This text capability is called hypertext, even though the implementation will not only be text that can be used as a link later.
Markup Language is called because HTML language uses marks, to mark parts of text. For example, text that is between certain signs will become thick, and if it is between other signs it will appear large. This sign is known as HTML tag.
If you want to see how HTML actually is, please right-click this page, then select View Page Source (in the Mozilla Firefox or Google Chrome Browser).
HTML is the core of all web pages. It is impossible to create a website without having a basic knowledge of HTML. Fortunately, HTML is also very easy to learn. You don't need to have a programming base or knowledge of any algorithm. The only ability needed is that you are quite familiar with how to use a web browser like Google Chrome or Mozilla Firefox.
