The purpose of this chapter is to introduce various traffic statistics that characterize the use and performance of the multimodal roadways traveled by the public. In addition, it provides an overview of the methodologies and processes used to collect various types of traffic data, and offer guidelines on how to analyze and evaluate the data and determine the most appropriate values to be used for project traffic development. A brief discussion on the sources and usage of “Big Data” is also included. Specifically, the following topics are covered in the chapter: