Confusion about the true Hijaab...

What exactly is 'hjaab' or 'purdah'?
Most people seem to be of the opinion that hijaab is a head cover, or refering to loose fitting garments while others take it to be full cover including the face. With the word 'purdah' i find that it refers to both men and women.
How would g man be observing purdah?
I would really like to know what exactly are the true laws of hijaab/ purdah for both men and women.
And why is there so much violation of laws when it comes to this matter? Is it a disputed matter?
I really look forward to your input.
Jazakumullahu khair
Abdur Rauf

We have not forgotten this question, brother. It requires a bit of a lengthy answer and we will respond Insha'Allah.

JazakAllah for ur patience.