what happened if we don't declare the title inside headings

Answer 1

It does not create any error your code will run fine
but in order to understand what current page is about for the user its better to have a title included in your heading.
It will simply display the title on top of your webpage

Answer 2

there'd be a problem in search engines for some browsers that people could not find your page title.
putting title tag between head tag is a recommended way for all browsers.

Answer 3

nothing

Answer 4

It would work fine.

Think of it like a book. You can still read a book even if it doesn't have a title, right? The title just tells you what it's called, and in no way affects the outcome of the webpage. So basically, if you get rid of your title, nobody will know what your website is called because it won't technically have a name.

Hope this helps.