While I have gone through a lot of information on w3.org about Doctype and understand the different types of doctypes (Transitional, Strict, Frameset)
I am still not clear what is the actual use of using Doctype on pages?
I mean:
Is it to prevent developers from using certain tags in the code (e.g. By using strict, we restrict the developer from using certain deprecated tags like font, center, etc)
Is it to give some information to the
browser and if yes, does it impact
rendering in any way?
Please help me with the same. Thank you.
It's to tell the browser how it should interpret the code in the page.
(If you use it as a tool to control developers, you have a management problem...)
The doctype does impact the rendering, what tags are valid, which attributes they can have, and also how you can use them in client script. A transitional doctype is more forgiving than a strict, but the HTML version also affects what's valid.
The biggest difference is between having a doctype tag and not having one, especially in Internet Explorer. Without a doctype tag it will render the page in quirks mode, which among other things include use of the non-standard box model, which can mess up your layout completely.