Should i use html 5 or not ?

Answer 1

HTML5 gives websites owners :

• Better Usability
• Improved Audio and Video Support
• Gaming Support
• Improved Mobile Support
• Saves Development Time

Go through this link for further reference :
https://tympanus.net/codrops/2011/11/24/top-10-reasons-to-use-html5-right-now/

Answer 2

It depends, if you are into web development, or hybrid mobile development the answer is yes, but it wasn't not clear what you want to do.

Answer 3

Also HTML5 tags are SEO friendly.

Answer 4

of course, it is more semantic if I don't mistake