The Importance of Correct HTML Syntax in Search Engine Positoning

There is a lot of competition to get good spots in the search engines. Proper
html syntax and a clean code will help toward better positoning.
With website design mostly done with wysiwig editors now, there seems to be a
lot of reliance on these tools without realising that they are far less than
perfect.
Software like frontpage tend to produce a fairly complicated html code and we
as users just assume that because it is software generated there won’t be any
problems with it.

Nothing could be further from the truth. Wysiwig software is very often unable
to properly integrate additional code e.g. affiliates links, adsense code,
shopping cart codes etc.
The more complicated the page, the higher the chance of there being a
problem with html.
It is quite surprising how many sites there are out there with html problems.
Just run a few competitors pages through the a validator and you will see.
Today’s browsers are extremely tolerant and will still display a page properly
that has all sorts of problems. But it is a different story with robots. They like it
simple and easy and will generally take the path of least resistance -- almost
human, aren’t they ?
So let’s say we have two competing sites, both are suitable for the top spot and
the search engine has a tough time deciding who to put first. There is a very
high chance that the validated site with proper syntax will be the winner.
Validation of the html on your site alone will certainly not secure you a high
rating, but as with so many other things it will help and might even be the
contributing factor to get you across the line.
Also a very important point for webpages using SSI, PHP etc. It is sometimes
difficult to validate code offline as there are many small bits that are put
together by the server. So you really don’t know what you will get in the end. Be
sure you validate all of these pages and do it with an online tool.
My favorite html validator is validator.org
And a case to the point: I recently installed a datafeed code for an affiliate site.
There was one error in the product display, two tr and td tags where the
wrong way around. And as each page listed over 20 products the errors of
course accumulated...
It will only cost you a bit of your time to validate and maybe a lot of time to fix
all the problems, but believe me it's worth it!
Go and validate!