The systemic study of natural world is called natural science. It is concerned with the understanding of natural phenomena based on collected data, knowledge or sense of experience by means of observation and experimentation. Natural science is subdivided into two main branches: one is biological science or life science which aims to study life and living organisms their function, structure, evolution, growth, distribution and taxonomy second is physical science which is also broken down into different branches, including Earth science, astronomy, chemistry and physics.