Psychology etymologically can be derived from two Greek words psyche, which means "soul" or "mind", and logos which means "study of”. Psychology is therefore is the study of or science of mind. Psychology studies the relationship between the mind and brain. Though originally started with human beings today we have animal psychology. Research uses animals to a great extent and draw parallels to human beings. Psychology is used to gain knowledge about the spheres of human activity including problems individuals face in daily life and also the treatment of mental illness.
Psychology uses various tools to gain insight into human behavior, one such tool is comparison. The branch of psychology that uses this tool is called comparative psychology Although the word Psychology is derived from the Greek word ‘psyche’, psychology does not specifically study only about the soul. It covers a wide area of human behavior. The most common definition used to define psychology is ‘the science of behavior and mental processes’.
Psychology though is a science differs from other subjects like sociology, anthropology, economics, and political science. As opposed to the other sciences psychology studies about the behaviour of individuals alone or in groups rather than studying the behaviour of groups. The same applies for biology and neuroscience. A clear differentiating line that marks off psychology from biology and neuroscience is that it not only studies about the neural response produced by the system but studies about the overall behaviour of the system.
The first person who called himself a psychologist was Wilhelm Wundt. The credit of opening the first laboratory for psychology also goes to Wilhelm Wundt. This laboratory was opened in 1879. Though a lot of terms were discussed and thousands of psychological questions were raised (for more details please refer ‘De Memoria et Reminiscentia or "On Memory and Recollection" written by Aristotle), psychology emerged as a separate field only recently.