Explain how data is stored on a hard disk.

Data is stored on a hard disk through a process that involves several steps:

1. Formatting: Before data can be stored on a hard disk, it must be formatted. This process organizes the disk into sectors, which are like tiny buckets that can hold data. Each sector typically holds 512 bytes of data.

2. Writing Data: When data is written to the disk, it is broken down into binary code, which is a series of 1s and 0s. This binary code is then converted into an electrical signal.

3. Storing Data: The hard disk uses a read/write head, which hovers above the disk platter. The electrical signal from the binary code is sent to the read/write head, which then changes the polarity of tiny magnetized regions on the disk to represent the 1s and 0s of the binary code. This is how data is physically stored on the disk.

4. Reading Data: When the data needs to be read, the process is reversed. The read/write head detects the polarities of the magnetized regions, converts them back into an electrical signal, which is then converted back into binary code, and finally back into the original data.

5. Locating Data: To locate data on the hard disk, the operating system uses a file system. This system keeps track of where data is stored on the disk, so when a file is requested, the operating system knows exactly where to look on the disk.

6. Deleting Data: When data is deleted, it is not immediately removed from the hard disk. Instead, the operating system simply marks the sectors where the data is located as available for reuse. The data remains on the disk until it is overwritten by new data. This is why deleted files can sometimes be recovered.