All the objects around us whether living or non-living are matter. Water we drink, food we eat, air we breathe, chair we sit on, are all examples of matter. Matter is anything that has mass and takes up space. Matter appears in a huge variety of forms such as rocks, trees, computer, clouds, people, etc. Matter embraces each and everything around us. Therefore, in order to understand the world, it would be necessary to understand the matter.

Each pure kind of matter is called substance. Here, pure we mean the same through out. Thus, aluminium is one substance and water is another. Please remember, the scientific meaning of substance is a little different from its every day meaning and we shall discuss it a little later in this lesson.