need a help in some css codes

Question

Sir,

 

I am in a little bit confused of some css codes and for what purpose they use. reply with the explanation of its use in details. here the code lines:-

 

1) div.menu 

 

2) div.menu ul

 

3) div.menu ul li 

 

4) div.menu ul li a, div.menu ul li :hover

 

5) div.menu ul li a : active

 

6) fieldset.login label

 

7)fieldset label:inline

 

 

Please reply with the explanation  regarding the use of above code lines.