Its woven star - shape contains five crossing points and can not be built from smaller knots, similar to the way a prime number can not be built by multiplying smaller numbers. (newscientist.com)
Pro tip: If your scarf isn't an infinity scarf but you want to wear it that way, simply tie the corners of the scarf or fringe together with small knots to create a temporary infinity scarf. (collegefashion.net)