I've been using the HTML Validation Plugin for Firefox for quite some time to validate my pages. Recently I learned that my page didn't validate at all, which confused me because the HTML Add On (HTML Tidy setting) was indicating I was valid. When I changed to SGML Parser as the option, now I'm beginning to see the errors, which I see on W3C.
Having said that, which option/method is the best to use? The ones listed are HTML Tidy, SGML Parser, or Serial.
I started checking this way because it is quick, rather than going to W3C's site directly. I'm open to other options if there are any.