HTML (Hypertext Markup Language) is a markup language used to create digital documents that can be displayed in a web browser. It is the language used to create websites and web applications. HTML is a markup language, meaning it uses tags to structure and format the content of a webpage. The tags tell the browser how to display the webpage's content. HTML is also used to define the structure of a webpage, such as headers, paragraphs, lists, and links. HTML can also be used to embed multimedia content, including images, audio, and video. HTML is the foundation of all web pages and web applications, and is the language used to create modern web content.
Markdown is not used for web development
It is an accessory for html, and does not do the same thing.
Markdown
CSS
The end result of using markdown is its conversion to valid HTML. It cannot replace HTML and is not an alternative standard, but it makes HTML easier to write.