Given the easy availability of 100s of web designing tools, every kid at the corner can stop vandalising the neighbour’s wall for a while, go home, “design” a website and upload it in a matter of a few minutes, and then come back and resume the vandalising. Yes, it is that easy to create web pages. But how do these pages fair in terms of SEO, load time and even usability? Abysmally. There is a reason why companies pay thousands of pounds to get websites designed by hand, with clean markup. And if you don’t know what’s the markup, it’s all that code that appears when you view the source of a web page.
Most GUI tools are terrible code generators. They create archaic code, and they create lots of it, even at places where no code is required. If you code by hand on the other hand, your markup is cleaner, and you keep away from inserting hundreds of unnecessary as well as deprecated tags. Search engines don’t like this, and there is a reason.
A cleaner markup means extremely light pages and it also means an increase in content-to-markup ratio. Search engines want more content and less code on your web pages. With less code on your page, your main content moves closer to the top and consequently, gets easily crawled. Remember that crawlers read only 150-250 words of your page and you should make sure everything important should be covered there. Pages with unnecessary and incorrectly nested code are difficult to crawl. They are also a hindrance to DOM scripting.
Accessibility is another important thing that gets compromised when you settle for unclean markup. If your web pages are not accessible to the visually impaired, they are not accessible to even the search engine crawlers because after all, a search engine crawler reads your web pages like a visually impaired person.
When you practice writing clean markup, you put things exactly where they should be, and this makes it easier for the search engines to find them. For instance, make proper use of the <h1>, <h2>, <p>, <ul> tags so that the search engine crawlers know what these tags contain
Use valid, semantic, lean, and accessible markup and it will significantly boost your rankings.