The water, like all the liquids, does not have its own shape and, if left free, it fills all the available spaces. 

It flows downwards attracted by gravity, but slowly and gently it can also flow upwards.

The water can also get into narrow spaces between one fiber and the other, making them swell, 
as happened to the paper in the experiment of secret messages. 

In the experiment of the rainbow, we have seen that water flows in the paper tubes carrying the colour with it.

This water property is called capillarity and it is very important. 

For example, it  helps water climb from a plant’s roots to the leaves in the tree top, 
walking through the tiny little tubes that are in the trunks of the trees or in the stems of the flowers, 
as we could see in the experiment of the colored flowers.