The management of agricultural crops at a spatial scale smaller than the entire field is known as site-specific management (SSM), or precision agriculture. The economic benefits of SSM practices must be considered before they can be widely adopted by farmers. For SSM to be justified, three requirements must be met: (1) there must be significant within-field spatial variability in the factors influencing crop yield; (2) the causes of this variability must be identified and quantified; and (3) the data from these measurements must be utilized to adjust crop management techniques in order to boost revenue or lessen environmental impact. This paper's goal is to examine the situation of SSM at the start of the new millennium and make some predictions about where it might go. The review is structured according to the fundamental elements of SSM mentioned above, which include measuring spatial variability, evaluating the information gathered from these measurements, applying the knowledge gathered to modify management procedures, and assessing whether the benefits generated outweigh the expenses.