Introduction
The characteristics of life are a set of foundational principles upon which all forms of life are built, including animals, plants, fungi and microorganism. These characteristics enable a living organism to interact with its environment, to utilize energy and resources, to grow and reproduce and to adapt to changing conditions. Understanding the characteristics of life is essential to being able to properly classify species and to understand how living creatures interact with their surroundings.

Characteristics of Life

Cellular Organization
All living things are made up of cells, which are the basic structural and functional unit for all life. Cells contain genetic material, proteins and other molecules which allow them to store energy, replicate themselves and interact with the external environment.

Metabolism
Living things must be able to metabolize food and other compounds to produce energy, which is essential for all physiological processes. Metabolism includes processes such as respiration, fermentation and photosynthesis, which break down food and environmental compounds and release energy which can then be used by the organism.

Growth and Development
All living things have the ability to grow and develop over time, increasing their size and complexity. This is due to the presence of genetic information which is passed on from parents to their offspring, as well as the uptake of new materials and energy from the environment.

Reproduction
Another characteristic of life is the ability to reproduce and the capacity to pass on genetic information. Living creatures have the ability to produce offspring that share certain characteristic with their parents, thus allowing them to pass on their characteristics from generation to generation.

Response to Stimuli
Living organisms are able to respond to stimuli, both from the external environment and from within the organism itself. This includes responses such as movement and changes in physiology, which allow the organism to adapt to new environments and conditions.

Adaptation and Evolution
All living things are able to adapt to their environment, which can lead to major changes in structure and function over time. This ability to change and adapt is essential for species to survive and drive the process of evolution, allowing species to change and evolve over thousands of years.

Conclusion
The characteristics of life are vital for all living creatures, allowing them to interact with their environment, to metabolize food, to grow and develop, to reproduce and to adapt to new conditions. Understanding these characteristics is essential for being able to properly classify species and to understand how creatures interact with their environment.