Use of face and style attributes

I find the 'face' and 'style' attributes in the complete webpage code like this:
<font size="4" face="Arial, Helvetica, sans-serif" style="arial">
What is the difference between face and style?
Also, why do we specify three values for face attribute?
Can anybody solve these doubts pls?

thank u very much

font face describes the face like arial chiller, ..etc., where as style means as Bold, italic underline

we can change the face 's style using style

we are using three attributes in face because

some browsers may dont support arial then it goes for Helvetica if not then other one

if dont use these font faces no problem the browser will take default font face

ok i tried my level best for solving above doubts ok