The correct use of HTML is something which is being looked at more and more by developers. It is surprising how many people use HTML wrong.
From my experience of browsing the internet I would say that most of the websites on the internet are still using old standards which have been known as bad practice for 4 years or more.
The internet is constantly changing and developers / designers need to adapt with it and not get stuck in the dark ages.
The biggest problem and my pet hate is tables for layouts this is about this worst thing you can do. Tables are for displaying tabular data. Not for putting your Photoshop cut up images into a design which you call a “website”. Most of the websites out there still use tables for their layout and use attributes such as align=“center”. If you look on the W3C website or w3schools you will find a full list of the current tags and which ones are deprecated.
http://www.w3schools.com/tags/default.asp
My second pet hate is FRAMES and IFRAMES and as with tables. I am not alone many respected developers agree that frames are bad and should die a long slow painful death. The problem is people still use them. Why use such bad technology when we have beautiful languages such as ASP.NET and PHP.
All the websites I have made over the past year have all conformed to XHTML 1.0 Strict or HTML 4.01 strict. I now make all my websites validate to XHTML 1.0 strict as it conforms to a better standard.
List of Recommended Doctypes by W3C
Don’t get stuck in the dark ages keep your HTML and standards up to date.