Mixin - a group of CSS declarations that canbe reused throughout the style sheet Can be thought of as a function for CSS
// writing a mixin for the box shadow property
@mixin box-shadow($x, $y, $blur, $c){
-webkit-box-shadow: $x, $y, $blur, $c;
-moz-box-shadow: $x, $y, $blur, $c;
-ms-box-shadow: $x, $y, $blur, $c;
box-shadow: $x, $y, $blur, $c;
}
// using the mixin
div {
@include box-shadow(0px, 0px, 4px, #fff);
}