It is called so because its operation is the opposite of a rectifier used to make DC, which already existed when the word was introduced. A rectifier flipped around or inverted.

In a USB plug the pins are tucked inside surrounded by ground, so they are not likely to get shorted by the plug falling onto a metal object. It would definitely damage the computer if they were. USB is low voltage, so it would never be dangerous to a person.

This is only possible in exceptional cases where the input data is highly repetitive, such as a simple digital drawing consisting of a few colors. Then the algorithm records how many bytes to repeat instead of writing them out one after the other. This is one of the most basic methods of how compression works.

Other methods include keeping a dictionary of sequences that have been encountered recently with the aim of using references into that table which are shorted than the data they describe, and prediction of a continuous signal, such as subtraction of the previous pixel in a row.

Most normal data that has a meaning is not very repetitive. It contains variations and noise, which make exact matches unlikely to occur. Typically compression achieves a ratio of 25% to 50%.

An "online" algorithm is not a meaningful classification. Perhaps you want to clarify what specific program you mean by online.

The operating system and the drive itself each have a level of cache to defer writes to the disk and combine them with others to make the process more efficient with less random seeking. USB keys are usually configured with writing cache disabled and are slower, particularly when copying many small files.

When the drive is instructed to turn off, all outstanding data is written to the disk. The heads also get retracted from the surface of the disks and parked on a dedicated ramp. The drive tries to do this in case power is suddenly removed, but won't be able to orderly write out any buffered data.

Viruses are not big enough to exhibit the complexity of a living organism. They can be compared to individual structures that exist inside a cell. Nevertheless, they can be physically destroyed like all things. You can apply a solvent to make its shell fall apart. Killing means making something stop functioning. You can "kill" a project or a running computer program.

If you made a stack of the particles next to or on top of one another, then you still wouldn't see them because the whole stack would be only 1 unit wide. If you had a pile of a significant width, the particles would probably be easily disturbed by wind and rise up like smoke. If the substance could burn, it would catch fire and explode easily, or settle down and cover surfaces like soot.