What does "styrofoam" mean? In what circumstances do you use it?

Native speaker’s answer
Rebecca
"Styrofoam" is a noun. It's a type of polystyrene! A lightweight, white plastic. It's usually used for packing materials and take-out coffee cups, so it's often used in relation to packing. Here, it seems someone made the cake out of styrofoam for display. Ex: Styrofoam isn't biodegradable, so it's considered harmful to the environment. Ex: We got some styrofoam cups for the picnic!