Life is all around us, both as multicellular organisms such as the iguana and bamboo above, as well as the unicellular microorganisms such as bacteria.  Life is present on every continent, in the air and in the waters of the world.  There is life even in the Mariana Trench, seven miles below the surface of the ocean.  As of 2010 biologists have described and classified 1.7 million plants and animals, and estimate that there are till over five million species still undiscovered.

This chapter will introduce the ways we study the science of Biology in the twenty-first century, the characteristics of living organisms and their classification.