Freight trains are sometimes illegally boarded by passengers who want a free ride, or do not have the money to travel by ordinary means. This is referred to as "freighthopping." A common way of boarding the train illegally is by sneaking into a train yard and stowing away in an unattended boxcar; a more dangerous practice is trying to catch a train "on the fly", that is, while it is moving, leading to occasional fatalities. Railroads treat it as trespassing and may prosecute it as such.