W3C Website?

I had never heard aboutthe W3C site until our last class... W3C is a web application that validates sites. It is a good validation service however not a good way to debug html. All you have to do is enter the url, and the document type from the drop down and if you see the green line saying congratulations, that means it has passed the standard requirements for that doc type. If not, you will see a list of errors. Some of the errors that we saw in class were:
1-Pars Mode error: This is when the Doc command is missing. Doc type needs to be specified before the htmal tag.
2-No character encoding found: This means that we need to have the correct css doc. It can be fixed by putting a meta tag. Meta tag itself means info about info....Information about structure on how it is stored (data). In html we out that in head and start with meta...Example: You can put things like keywords,author name etc.
3- Alt tags need to be error: If another application cant read the doc, then it needs the alt tag. Alternatively if the picture got deleted, then words would show up on the page. A classic example for this is Internet spiders. Some other application exaple can be for blind people, which reading(audio) the text is used rather than displaying.