moonbiter - 11:45 am on Feb 7, 2006 (gmt 0)

I am really confuse now. What is strict and what is transitional really? Will I be wrong in using either one? How do I know when to use what?

According to the HTML 4.01 Transitional DTD:

... the HTML 4.01 Transitional DTD, ... includes presentation attributes and elements that W3C expects to phase out as support for style sheets matures. Authors should use the Strict DTD when possible, but may use the Transitional DTD when support for presentation attribute and elements is required.

So, if you need support for deprecated presentational elements [w3.org] and attributes [w3.org] then use the Transitional (also called "Loose") DTD.