Things around us can be divided into two groups: living and non-living. We are surrounded by living and non-living things.
Living things are alive; they have life in them.
Non-living things do not have life in them.
All animals and plants are living things and biology is the study of these living things.
A cat playing with a ball is obviously living. A pigeon flying from tree to tree is also a living thing. Plants are living things but they do not play with balls or fly.
Sand, wood and glass are all non-living things. Paper is non-living but it is made from trees. Jam is also non-living but it was made from the fruit of a plant.
For something to be living, it has to show all of the characteristics of living things.