HTML Doctype very first thing? [duplicate]

HTML Doctype very first thing? [duplicate]

References

Reference NO 1

http://www.w3schools.com/tags/tag_doctype.asp

Reference NO 2

http://stackoverflow.com/questions/13132558/multiple-doctypes-in-a-single-html-document

Reference NO 3

http://stackoverflow.com/questions/6076432/why-do-i-need-a-doctype-what-does-it-do

Reference NO 4

http://msdn.microsoft.com/en-us/library/office/aa218654(v=office.11).aspx

Reference NO 5

http://www.bobasyourguide.com/html_code_tutorial/html_doctype_and_character_encoding/

Reference NO 6

http://wordpress.org/support/topic/699901

Reference NO 7

http://www.icesoft.org/JForum/posts/list/15782.page

Reference NO 8

http://www.pagetutor.com/html_tutor/lesson24.html