Memory foam pillows offer a unique material based on the properties of its cell structure. Unlike standard foam pillows that only partially compress when under pressure, the cells in memory foam pillows fully compress when the weight of the head is pressed upon it, then the pillow springs back to it's original shape very slowly. This is how the name "memory foam" came to be, the foam appears to remember the shape of your head when it was last placed upon it's surface.
Memory foam pillows are also temperature sensitive. This means that at lower temperatures it is harder and more viscous, while at higher temperatures, it is softer and more elastic. This is the reason memory foam pillows called visco-elastic.
