From microorganisms to whales, from single cells to complex organisms, from plants to animals to fungi, from body plans to behavior, the diversity of life is amazing. Living organisms have a profound impact on our physical world of ocean, landscape, and climate; around us is a multitude of diverse ecosystems that provide a livable environment and many valuable resources. The study of life—biology—is a multifaceted endeavor that uses observation, exploration, and experiments to gather information and test hypotheses about topics ranging from climate change to stem cells. The field of biology is so diverse that it can sometimes be hard for one individual to keep its breadth in mind.