what does the other img represent, what is this? I understand that the class called img is going to be applyed on the div tag in the html body but what is the other img?? is this like a recursion in programming something inside something?
What this selector means is that you are going to select an image element that is within a div element that has been assigned a class called "img". So for example, this is the image element that would be selected...
i dont know why w3c schools did not mention this kind of thing
W3Schools is great for a beginners, simple overview. The site has some mistakes, but most importantly, that site should not be confused with the W3C.
and by the way how is this syntax called
Its just known as "Seletors". Selectors may range from simple element names to more complex representations. Take a look at this article on the W3C site that goes into Selectors in much more detail. This article covers CSS3.