In SASS, what syntax is used to denote a variable? code example

Example 1: scss variables

$base-color: #c6538c;
$border-dark: rgba($base-color, 0.88);

.alert {
  border: 1px solid $border-dark;
}

Example 2: variables scss

// SCSS variables

$darkcolor: #605C4D;
$large: 350px;

section{
	background-color: $darkcolor;
  	height: $large;
}