A rash is a change in the appearance of your skin. Most rashes make you look like you are covered in little red dots. Some rashes are raised, some are blistery, still others are flakey. There are lots of different kinds of rashes and even more possible causes, so if you have a rash that is very bad or won't go away, see your Doctor.
Trash, rubbish or garbage is all the things that we don't use and throw away. You put your trash in a bin or trash can and it gets taken to the tip. Some people just litter the street with their rubbish.
Trash is mostly made up of plastic packaging from food, and scraps of food.