 Alright, so let's think about the different kinds of life for a few minutes. If you think of all the different kinds of organisms that exist on Earth, there's much diversity there. We can break all the different kinds of living organisms into three different domains. There's the domain archaea, the domain bacteria, and the domain eukaryon. The domain archaea includes unicellular prokaryotic organisms that represents some very ancient life forms. For example, some of the members of the domain archaea live in very hot environments or some live in very extremely salty environments, so they're some really unusual organisms. The domain bacteria are also composed or is also composed of unicellular prokaryotes, and these are what we refer to as typical bacteria like streptococcus that might make someone sick. The domain eukarya is composed entirely of eukaryotic organisms, and this domain eukarya is broken up into four groups. One group we collectively refer to as the protist, and the protist is made up of a group of many different kingdoms, but these may be unicellular or they may be multicellular. This includes things like the multicellular algae like olva or spirogyra. It includes unicellular organisms like amoebas or euglena or paramecium are some common ones. So the other three groups are kingdoms. One is the kingdom fungi. Fungi are like mushrooms and yeast, puffballs. These are all heterotrophic as a general rule, they're decomposers, and their cells have cell walls made of a substance called chitin. The kingdom anemalia of course are animals. Animals are heterotrophic, but they're consumers. Heterotrophic means that they must find a ready-made source of organic food. They can't make their own organic food. Animals unlike the fungi have no cell walls. The kingdom plantae of course includes the plants, and you're familiar with plants, trees, grass, etc. Our plants and these organisms are autotrophic. That means that they can use an energy source to make their own organic food, and of course plants use sunlight and carbon dioxide to make their own organic food source. And plants have cell walls made of a substance called cellulose. So when we think about the diversity of life on earth, we can arrange it into three different domains and then within the domain you carry it, there are the protist, fungi, animals, and plants.