BD and DVD both have holes and bumps. The difference between the two is that the holes and bumps of the BD are smaller and closer together. A blue laser is used to read the BD. The BD has spiral tracks that go from the center of the disc towards the edges. Information is stored in these tracks in the form of audio and video. The blue laser used to read this information has a wavelength of about 405 nanometers and must be much more precise than that of a DVD because the holes and bumps are smaller and closer together. Figure 2: Several lasers reading a DVD and a BD. Figure 2 presents an image of a DVD and a BD. As can be seen on the DVD, the holes and bumps are larger and therefore the laser is less precise than that of the BD. Blu-Ray disc can play MPEG-4 and MPEG-2 encoded formats. BD is also used for data storage, 1080p HD video and audio playback, 3-D stereo, and has many other uses. The DVD player is not only used to play the data in a DVD, but also to write the content to a DVD. As mentioned above, a DVD has holes and bumps like a BD in the tracks that contain information. This information can be video, audio, or a combination of both. When a DVD player reads this data, the smooth surface of the disc is treated as "0" and the holes are read as "1". Reads DVD and converts data to binary code. Unlike a BD, a DVD uses a red laser with a wavelength of around 600 nanometers. This is 180 nanometers less than a CD but 200 more than a BD. This allows it to have a higher density of holes and bumps than a CD but lower than a BD. Originally only single-layer DVDs were released, but later dual-layer discs were released. Single-layer disks can hold up to 4.7GB of data while dual-layer disks can hold up to 17GB of data. A DVD does not have the capacity to contain high definition films. An MPEG-2 compression system is then introduced. When used, the data will be encoded on the DVD as changing frame elements. This must be successfully decoded and decompressed by the DVD player.