Lets go line by line
<!DOCTYPE html>
- HTML5 Doctype
<html xmlns="http://www.w3.org/1999/xhtml">
- Refer here
<head>
- Document head
element
<meta name="Generator" content="some info here ..." />
Description of the program you used to create the HTML document
<meta charset="utf-8" />
- Document Character Encoding, Good read
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1" />
Read Here And Here
I would've certainly wrote a big fat description for each but realized that these were already asked in different questions, so thought to link them instead of repeating the same thing here again.