Close your eyes. Imagine yourself walking through a park or a forest. Look around and see the beautiful flowers and the plush grass, the tall trees and wild berry bushes. Now look closer. What do you see? Do you see bees fluttering around the roses and sunflowers or the blue jays picking at the ground and gathering up twigs? Or is it the family of deers prancing and having an afternoon snack that you see? The bees, birds, and deers are all showing examples of interactions in nature: an interaction that involves animals and plants and depends on both to keep the cycle going.
The bees and the flowers that you visualized are examples of plant/insect interactions. The bees gather nectar for their honey while collecting pollen for the roses. The bees need the nectar to live. They need to make honey for the Queen Bee. The flowers need the bees to distribute pollen so the flower can reproduce. Without one of these species, both of these species would not exist.
Remember the trees you saw? How about the birds? These two organisms in nature complete a plant/animal interaction. The birds pick up the fallen branches and make a nest in the tree. The birds also jostle around the branches and leaves which helps spread the seeds to reproduce the tree. This relationship also is need for the continuation of both organisms.

Plant and animal interactions are vital for the survival of both plant and animal. You really can't have one without the other. Believe it or not, we as humans need these relationships to survive ourselves. Bees, and birds, and deers pollinate the food that we need to live. These interactions are so important to our worlds botanical make-up.