Archaeologists study human history, cultures and behavior, starting with the beginnings of human history. They do this by examining materials that remain, usually underground, from past human societies. From studying the ruins of buildings, tools, pottery, jewelry and other artifacts, archeologists try to piece together knowledge of how people used to live. Many archeologists study prehistorical periods, before humans started creating written records of their thoughts, while others focus on more recent history and include diaries and other written artifacts in their research.
Most undergraduate archaeology programs are in liberal arts colleges that do not ask you to declare a major until sophomore year. Therefore, in high school, you need to take the same courses that are required for admission to any liberal arts program: a variety of English, history, math, laboratory science and foreign language courses. However, if you plan to write in your application that you intend to major in archaeology, it is important to have especially good grades in history and science classes. If you can, take courses in anthropology, geography, statistics, art history and physical sciences such as geology or environmental science.
Few undergraduate colleges have an archaeology department, but many anthropology programs will allow you to concentrate in archaeology, or to create an interdisciplinary archaeology program of your own. Generally, an archaeology major consists of courses in archaeological theories and methods, statistics, life sciences, languages and history. Some offer field experience for undergraduates at actual excavation sites. For the requirements at individual schools, check the websites at the colleges that interest you. For example, to major in archaeology at Boston University, you must take Introduction to Archaelogy, Archeological Science, Methods and Theory of Archaeology, two courses in Cultural Anthropology, one statistics course, one "topical" course such as the origins of agriculture or the rise of civilization, and three "area" courses that are devoted to a specific region or culture. Simon Fraser University, on the other hand, requires two topical courses and just one regional course; they also require courses in Material Culture Analysis, Archaeology of the Old World, Archaeology of the New World, a laboratory course such as archaeobotany or zooarchaeology, and either Human Osteology or Quantitative Methods in Archaeology.
If you plan to get a master's or doctorate degree in archaeology, your college transcript is important. It is best to major in archaeology, although graduate programs might consider you if you have a degree in anthropology, human geography or a related field. They also favor applicants who have field experience in archaeology, and previous research experience -- so try to get an undergraduate internship and write a senior thesis in archaeology.