Geographic Information Systems (GIS) are concerned with the collection, management, display, and analysis of spatial data. In order to utilize GIS, one needs to have appropriate hardware, software, and trained personnel. However, the cost of this portion of an automation project is small compared to that of data collection, which is very expensive. Moreover, the accuracy and quality of data required for different applications is not usually homogeneous. In this paper, a comprehensive outline of the different types of errors encountered in the process of data collection is presented. An overview of different errors encountered in the primary and secondary methods of data collection is explained.