+ selector css

h1 {
  color: red;
}

In this CSS code example that sets the color of all h1s to red 
the "h1" is the selctor because we are applying this style to 
the h1s.div + p {  
   color: green;  
} 
/* Answer to: "" */

/*
  In CSS, selectors are patterns used to select the
  element(s) you want to style.

  Use this CSS Selector Tester that demonstrates the different
  selectors:
  https://www.w3schools.com/cssref/trysel.asp
*/

p[title~=beautiful]:hover {
  color: orange;
}

<p title="beautifull">I can't be beautiful</p>
<p title="beautiful">Hover to make me beautiful</p>