Steam locomotives have long used a loud whistle to warn people at crossings and signal departure from a station, and that sound became closely linked with rail travel in popular culture. As steam trains were replaced by diesel and electric services, the whistle survived mainly as a symbol of an earlier, slower way of travelling. Online, creators now reuse it to add instant period atmosphere to travel vlogs, model railway videos and history edits, because listeners recognise it immediately even without seeing a train.