According to Feng Shui, there are five elements in nature. These are wood, fire, earth, metal and water.
These elements are inter-related in two ways, which means that there are two types of cycles of these elements–the productive cycle and the destructive cycle.

Productive cycle of elements
You can see in the above sketch that wood produces fire, which means that you can produce fire by burning wood.
Fire in turn produces earth, because the fire burns and creates ash (earth).
Earth produces metal, because metal is mined from the earth.
Metal produces water; this is because metal can be melted and then it acquires liquid state like water.
Water produces wood because by watering only we can grow plants!
A beginner may take a while to understand the cycle of elements, but once you understand it properly, it is very easy to use it for enhancing your house.

Destructive cycle of elements
In the above destructive cycle of elements, you can easily see that wood destroys earth, because trees grow on earth and suck away all minerals and leave the earth barren.
Fire destroys metal, because fire melts the metal.
Earth destroys water, because earth (mud) absorbs all the water, when it rains.
Metal destroys wood, because implements made of sharp metal can cut the trees.
Water destroys fire, because water can put off any fire.
Understanding these two cycles of production and destruction of elements will help you understand the reasoning behind many enhancing measures of Feng Shui.