The kingdom Animalia includes multicellular organisms whose cells have a membrane-bounded nucleus. Animals are unable to make food from the sun, and need to eat to obtain nutrients.
The kingdom Plantae includes multicellular organisms whose cells have a membrane-bounded nucleus. Plants are able to make food from the sun through photosynthesis.
The protists consist of a group of simple organisms that could be single-celled or multicellular. They do not have specialised tissues and can be found in almost any aquatic or moist environment. This group used to include organisms such as protozoa, slime moulds and algae but this is no longer the case. Modern taxonomists have classified the green algae and red algae in the kingdom Plantae while the brown algae are either in their own kingdom or included as part of the protists. We have included all brown algae in the kingdom Protista only for simplicity sake as the taxonomic classification is still in flux.