Machines and devices based on reactive ai dont have a concept of the past, historic data and inferences from it nor the ability to conceive the future. Such machines work on the present, a scenario or a task that is right in front of them. Deep Blue, the famous supercomputer developed by IBM that won against Gary Kasparov in chess is an example of this. The system did not know how to look at the bigger picture of chess piece sacrifices nor strategic thinking skills. All this Ai knew was howe to choose the most appropriate move from the list of available moves available depending on the boards layout. This is an example of a reactive machine because the chess Ai wasn't able to predict the future or remember the past. All it did was look at the board and pick the most logical move.