When you drive on a highway from a city to another city, you may get slow down due to an accident ahead. This accident may cost you at least a half-hour delay. If you have a friend or family member in your car, then he/she may help you by using an app in the smart phone. This app can collect information from cars on the road and then gives you an advice how to go around the accident. This scenario is not a fiction. It is a real experience of many drivers. This app is an application of crowdsensing, which is also called the participatory sensing.