In order to identify living things, biology books give several characteristics to identify them. Some of the characteristics of living things suggested by biologists are as follows:

• They are highly organized in comparison to nonliving things.
• They display homeostasis, which means that they maintain a relatively constant internal environment.
• They can grow, reproduce, and develop from simple beginnings.
• They intake matter and energy from the environment and can transform them into other forms of matter and energy.
• They show response to stimuli.
• They show adaptation to their environment.

Based on some of these characters, the vacuum cleaner, potato, and humans are assessed as given below:

             + sign indicates fits the life score; – sign indicates does not fit the life score.

The process trying to define things as living or non-living is obscure based on this scoring exercise. Vacuum cleaners are non-living machines that are used to remove dust. They use the matter and energy from the external environment and transform the energy for their work. Vacuum cleaners and old animals are similar in the sense that they cannot reproduce or grow or develop. Potatoes are living things, but they are not responsive to any sort of stimuli. Human beings are living organism and fit all the characteristics of living things. Also, it is a known fact that all the living things are made up of the same elements, compounds, atoms, and molecules from which non-living things are made.