Check out example codes for "html lang en-us or en-US". It will help you in understanding the concepts better.

Code Example 1

<!DOCTYPE html>
<html lang="en-US">
  	<!-- Specifies the document lauguage
 	(United States English) -->
</html>

Code Example 2

<!DOCTYPE html>

<html lang="en"> <!-- sets language to english -->
  
<!-- <head>, <body>, etc. contents-->

</html>

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