1. An information terminal capable of being mounted on a vehicle and capable of executing applications, the information terminal comprising: a categorizer configured to categorize the applications into categories; a selector configured to select a priority application from each category according to a driving situation of the vehicle, the priority application being defined as an application to be executed with higher priority than any other application in each category; and an executer configured to execute the priority application selected by the selector, wherein the categorizer categorizes the applications into the categories according to their use so that similar applications with similar uses are categorized into the same category, the vehicle has an obtaining device configured to obtain actual measurement values of parameters for identifying the driving situation, the categorizer assigns the parameters and parameter thresholds to the categories separately, and the selector selects the priority application by comparing the parameter with a corresponding parameter threshold in each category.