./ = means "here", in current folder
../ = exit current folder (go to parent folder)
/ = goes to utmost root folder / root level of domain

file:/// + browse files and folders offline (works in chrome)

http:// = open external web adress 
https:// = open external web adress with SSL encryption



to link this :
<p><a> href "./

in html under tittle:
<link rel= "stylesheet" href="css/style.css">

in web 1 make new folder "css"