In biology, an organism is any of a wide variety of living creatures composed of interdependent parts capable of performing vital functions. However, there is some semantic dispute that this classical definition is too broad for current scientific understanding in that it potentially describes viruses and even technological life forms. Many alternative definitions exist within specific scientific and philosophical disciplines.
Biologically, any ambiguity surrounding the word "living" in the definition of an organism is addressed by several qualifications, the criteria for "life." Life, on the species level, is expected to have some capacity to respond to stimuli, grow and develop, maintain homeostasis through self-regulation and reproduce. Viruses may or may not be considered living organisms because they are incapable of independently meeting several of the qualifications and require the cells of other living organisms to carry out vital functions.
All organisms share certain characteristics. All are made up of cells, microscopic membranes containing, among other necessary features, the organism's DNA. All organisms rely upon that DNA as the blueprint for reproduction and the continuation of their species. All known organisms are believed to have evolved from a common ancestor, thus all DNA is shared to come degree. Finally, all organisms eventually die.