Many phenomena are better understood by describing their causes and effects. When scientists see a connection between one fact and another, they try to show a cause-and-effect relationship. The cause explains why something happens. The effect describes what happens. Almost all writing about science and nature is concerned with cause and effect. For example, why does the ocean's tide move into and out of the shore? In what way does the moon effect this? The answer is that there is a cause-and-effect relationship between the moon and the movement of the ocean. There are several ways to express this.