When we look around us we see many object each of which excites our curiosity, for example, the observation of matter raises the question as to why some of the matter is solid, some is liquid or some other is gas? Likewise when there is thunder or lightning of the clouds we wish to find the answer to such questions; how are the clouds formed and from where did the lightning and thunder originate? Why is a plastic comb that has been run through the hair acquires the property of attracting small pieces of wooden chips, hay and paper? Why does a pebble fall farther when shot through a sling shot (catapult) than when it is thrown by hand? What is the nature of heat and how is light produced? All there question have been agitating the mind of man since the beginning. That branch of science which endeavors to find answer to these and other similar question is called Physics. Thus we can define :

Physics is that branch of Science which offers the study of the properties of matter and energy along with the inter action between them.

Originally Science had two main branches, one of these consisted of Physical Science and the other of Biological Science. With the progress in these sciences it was felt necessary to sub-divide them further. Thus the physical sciences were divided into physics astronomy and chemistry.
In the present era the research in physics has so much increased its sphere that it is found necessary to undertake the study of physics under different branches.