There are three sectors of an economy: primary, which deals with extraction of raw materials; secondary, which is the manufacturing of raw materials into the finished product; and the tertiary sector that deals with intangible goods and services.
Since we do not mine raw materials, nor do we manufacture raw materials into products to export, Guam’s economy is largely dependent on the tertiary sector, which includes retail, tourism, banking, entertainment, and IT services. These are the factors that drive Guam’s economy.