This computer science video is about the lossless data compression technique known as Run Length Encoding (RLE). It begins by mentioning the benefits of data compression, and the difference between lossy and lossless compression formats. It then explains how the technique of run length encoding can be applied to a simple data set, of the kind that might be generated by a data logging application. It also illustrates how run length encoding might be applied to an indexed bitmap. The suitability of run length encoding, depending on the nature of the data, is discussed. The possibility of negative compression is also demonstrated. Different variations of run length encoding are mentioned, as well as its role as a small but important aspect of more complicated compression algorithms such as JPEG.