Let's break down the definition of science.
Science is practical. Although science sometimes involves learning from textbooks or professors in lecture halls, its primary activity is discovery. Discovery is an active, hands-on process, not something done by scholars isolated from the world in ivory towers. It is both a search for information and a quest to explain how information fits together in meaningful ways. And it almost always seeks answers to very practical questions: How does human activity affect global warming? Why are honeybee populations suddenly declining in North America? What enables birds to migrate such long distances? How do black holes form?
Science is based on observation. Scientists use all of their senses to gather information about the world around them. Sometimes they gather this information directly, with no intervening tool or apparatus. Other times they use a piece of equipment, such as a telescope or microscope, to gather information indirectly. Either way, scientists will write down what they see, hear and feel. These recorded observations are called data.
Data can reveal the structure of something. This is quantitative data, which describes an object numerically. The following are examples of quantitative data:
Notice that quantitative data consist of a number followed by a unit. The unit is a standardized way to measure a certain dimension or quantity. For example, the foot is a unit of length. So is the meter. In science, the International System (SI) of units, the modern form of the metric system, is the global standard.
Data can also reveal behavior. This is qualitative data, which are written descriptions about an object or organism. John James Audubon, the 19th-century naturalist, ornithologist and painter, is famous for the qualitative observations he made about bird behavior, such as this one:
Next we'll learn about science as a systematic, intellectual pursuit.