The term "psychology" was first coined in 16th century Germany as a combination of two Greek root words: "psyche" (soul or mind) and "logos" (study). Its original use suggested "the study of the mind", something as old as the human race itself. In recent centuries this interest in human nature has been honed into a systematic discipline. Today psychology is defined as the science of behaviour and mental processes.
The scope of psychology includes many different fields, distinguished by interest in different psychological processes, different populations, and differeent levels of analysis. Professionals psychologists may be interested in basic research or applied techniques like therapy, or they may study humans or animals. They may focus on either internal or external processes, on changes among individuals or over time, and on the influence of either human nature or specific situations.
Because psychology is a science, all fields of psychology rely on the scientific method. The scientific methold is a way of acquiring knowledge. This particular method emphasizes the study of how real events are experienced through one's senses, a perspective known asempiricism. Empirical research is research based on the evidence of sensory experience. A scientist conducts empirical observations, records measurements(data) of these events, and makes guesses(hypotheses) about their causes and connections. Many hypotheses about similar sets of events are summarized in theories, which are models or broad explantions of cause-and-effect connections.
In conducting scientific research on behaviour and mental processes, psychologists may study either human or nonhuman subjects. Research can be conducted in the natural settings where the events occur(referred to as the field) or in the laboratory, which is any controlled environment. In laboratory research, psychologists control who the subjects are as well as the conditions they ecounter. In all research, whether human or nonhuman, field or laboratory, psychologists record their observations and formulate hypotherses in order to explain behaviour and mental processes. The goal of psychology is to understand, predict, and control behaviour and mental processes.