Anthropology as defined by the American Anthropological Association:

Anthropology is the study of humans, past and present. To understand the full sweep and complexity of cultures across all of human history, anthropology draws and builds upon knowledge from the social and biological sciences as well as the humanities and physical sciences. A central concern of anthropologists is the application of knowledge to the solution of human problems. Historically, anthropologists in the United States have been trained in one of four areas: sociocultural anthropology, biological/physical anthropology, archaeology, and linguistics. Anthropologists often integrate the perspectives of several of these areas into their research, teaching, and professional lives.

Specifically:

• Sociocultural Anthropology
  Sociocultural anthropologists examine social patterns and practices across cultures, with a special interest in how people live in particular places and how they organize, govern, and create meaning.
• Biological (or Physical) Anthropology
  Biological anthropologists seek to understand how humans adapt to diverse environments, how biological and cultural processes work together to shape growth, development and behavior, and what causes disease and early death. In addition, they are interested in human biological origins, evolution and variation.
• Archaeology
  Archaeologists study past peoples and cultures, from the deepest prehistory to the recent past, through the analysis of material remains, ranging from artifacts and evidence of past environments to architecture and landscapes. Material evidence, such as pottery, stone tools, animal bone, and remains of structures, is examined within the context of theoretical paradigms, to address such topics as the formation of social groupings, ideologies, subsistence patterns, and interaction with the environment.
• Linguistic Anthropology
  Linguistic anthropology is the comparative study of ways in which language reflects and influences social life.

Source: http://www.aaanet.org/about/WhatisAnthropology.cfm