About (X)HTML validation
If you want to make sure your HTML pages are W3C valid,
before publishing, you can go on and check them using the:
The W3C's HTML validator is the "de facto" standard on HTML validation field. But if you need a second opinion, there are a couple you can ask:
* Unfortunately, except for the W3C Validation Service and Dr Watson, all the others are out of date. Most of them are in fact "dead projects".
Due to a great amount of "generated" HTML used in the course pages you have seen here, there is no guarantee they will be W3C valid. In fact they will probably not.
I have made my best to make all possible pages HTML5 valid if you see anything that could be better, please, let me know.
A last piece of advice about the validation process:
Never ever put a "valid logo" on an invalid page.
Get used to re-validate your page before republishing, even you are pretty sure you don't introduce any error when making changes.
If there is a chance the page becomes invalid, don't put the "valid logo" on it.
AVOID TO BE ON THE WORLD's WORST WEBSITE LIST
To know the don'ts you need to click here.
DO IT RIGHT !
YOU WANT TO BE ON THE BEST WEBSITE LIST, DON'T YOU ?
To know the dos from the best, you need to click here.
WHAT TO DO NEXT
Here you will find a bunch of very basic information. My intention is a very basic introductory HTML course, focusing on people with no web development knowledge at all.
What do you get here is just the beginning. Many of what you have seen, is not to be used next.
Tables (used for formatting), frames, HTML formatting options and things like that, you must know it exist but nowadays there are much better ways to get the job done.
From here you can go ahead with your studies using the HTML 4.01 Specification.
And as soon as possible, you should give HTML 5 Specification a try.
Good Luck and All the Best!