according to my search on wikipedia,..
"Social work is both a profession and social science. It involves the application of social theory and research methods to study and improve the lives of people, groups, and societies. It incorporates and uses other social sciences as a means to improve the human condition and positively change society's response to chronic problems.
Social work is a profession committed to the pursuit of social justice, to the enhancement of the quality of life, and to the development of the full potential of each individual, group and community in the society. It seeks to simultaneously address and resolve social issues at every level of society and economic status, but especially among the poor and sick.
Social workers are concerned with social problems, their causes, their solutions and their human impacts. They work with individuals, families, groups, organizations and communities.
Social work and human history go together. Social work was always in human societies although it began to be a defined pursuit and profession in the 19th century. This definition was in response to societal problems that resulted from the Industrial Revolution and an increased interest in applying scientific theory to various aspects of study. Eventually an increasing number of educational institutions began to offer social work programmes.
The settlement movement's emphasis on advocacy and case work became part of social work practice. During the 20th century, the profession began to rely more on research and evidenced-based practice as it attempted to improve its professionalism. Today social workers are employed in a myriad of pursuits and settings.
Professional social workers are generally considered those who hold a professional degree in social work and often also have a license or are professionally registered. Social workers have organized themselves into local, national, and international professional bodies to further the aims of the profession."
as for me, its simple... social work is an interactions between human beings and their environment, and the capability of people to perform their social functioning.