What does symbol tilde (~) mean in CSS [duplicate]

Question

I want to know what does (~) mean in css.

#img1:hover ~ #img2 {     opacity: 0; } 

In visual studio, i get 'unexpected character sequence' error when i use this symbol. what is the actual meaning of this in CSS. what does it do?

Answer 1

http://www.w3.org/TR/selectors/

8.3.2. General sibling combinator

The general sibling combinator is made of the "tilde" (U+007E, ~) character that separates two sequences of simple selectors. The elements represented by the two sequences share the same parent in the document tree and the element represented by the first sequence precedes (not necessarily immediately) the element represented by the second one.

example

h1 ~ pre 

matches that <pre> here:

<h1>Definition of the function a</h1> <p>Function a(x) has to be applied to all figures in the table.</p> <pre>function a(x) = 12x/13.5</pre> 

There is also + selector, for adjacent sibling combinator: with h1 + pre the <pre> tag would have to be right after <h1>