Travelers are increasingly turning to smartphone applications for an array of transportation functions. Four types of transportation apps have emerged: 1) mobility apps; 2) connected vehicle apps; 3) smart parking apps; and 4) courier network service (CNS) apps. This chapter discusses the history and trends leading to the growth and development of transportation apps and summarizes key characteristics of 83 transportation apps identified through an Internet search cataloging transportation apps with more than 10,000 downloads each. Seventy-one percent of the 83 apps identified incorporated a real-time data function (e.g., traffic conditions, roadway incidents, parking availability, and public transit wait times). Additionally, the chapter reports on findings from a survey, conducted in spring 2016, of 130 app users who downloaded the RideScout mobility aggregator app (which ceased operations in August 2016). The survey, was asked questions about their use of mobility aggregators more generally, sought to understand how multimodal information apps shift travel behavior. The findings showed that most users of such apps would walk, drive alone, and carpool during a typical month. Fifty percent of respondents drove alone once or more per day. Twenty-five percent owned one vehicle, and 75% owned two or more vehicles. Thirty-nine percent of respondents reported that they drove less or much less due to the apps. Findings from the survey suggest that multi-modal app users do change their travel behavior in response to information provided, and they may contribute to a reduction in vehicle use.