The word organism is used to describe any living thing in reference to its organs, organelles, or other parts that work together to carry on its various tasks or jobs of life. Some examples of organisms are the plant, an animal, a bacterium, a protist, or fungus.
- Main Page: Taxonomy
Taxonomy is a branch of science focused on the classification of organisms into an ordered system. The system involves grouping organism based on the characteristics they share in common. All organisms within any given group possess features that are common to all members. Each group is then subdivided so as to further distinguish its members based on their differences. This hierarchy of groups and subgroups provides a systematic method for classifying and naming organisms ranging from very general similarities to ever increasingly detailed.
The Taxonomic Hierarchy:
- Main Article: Trophic level
Organisms are characterized by a specified kind of nutrition, way of obtaining energy, or their position in a food chain, which are known as their trophic level. Plants are in the first trophic level as the producers, herbivores eat the plants so they are in the second trophic level as the consumers, and most carnivores are in the last trophic level as the consumers. 
There are three basic types of organisms based on their broad trophic level or position within a food chain.
- Producers -- plants which are capable of photosynthesis
- Consumers -- animals, which can be primary consumers (herbivorous), or secondary or tertiary consumers (carnivorous).
- Decomposers -- bacteria and fungi, which degrade organic matter and restore minerals to the environment.
- Organism Encyclopedia Britannica