An Alternative Definition for IQR. In some texts, the interquartile range is defined differently. It is defined as the difference between the largest and smallest values in the middle 50% of a set of data. To compute an interquartile range using this definition, first remove observations from the lower quartile.
A hard drive is a device used to store data in a semipermanent state on your computer. Computer memory is a series of small packets of data called bits. Each bit is a 1 or a 0, and each bit is stored as a small magnetic charge on the hard drive. A read/write head moves over the hard drive to retrieve or rewrite the bits as needed.
The Hard Drive on your computer is where all your files are stored. Not only that, it's the place where the Operating System itself is installed. A hard drive is a physical thing inside of your computer. If you were to take it apart, you'd see one of more disks (called platters), one on top of the other. In a modern hard drive, however, there's usually just one platter. The disks are magnetised and can be written to and read from.