05. What is character encoding in html?

ASCII was first character encoding standard (character set)
ASCII defined 128 different alphanumeric characters such as number (0-9), letter (A-Z) and some special characters like ! $ + - ()
Meta tag charset should be first meta page in HTML document
HTML5 character encoding is UTF-8 unicode

Some more information.

Example:

<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <meta name="description" content="I am a web page with description"> 
  <title>Home Page</title>
</head>
<body>
  
</body>
</html>