Wikipedia
Hot swapping is the replacement or addition of components to a computer system without stopping, shutting down, or rebooting the system hot plugging describes the addition of components only Components which have such functionality are said to be hot-swappable or hot-pluggable likewise, components which do not are cold-swappable or cold-pluggable Most computer hardware, such as CPUs and memory, are only cold-pluggable However, it is common for high-end servers and mainframes to feature hot-swappable capability for other components, such as PCIe and SATA drives A well-known example of hot swap functionality is the Universal Serial Bus (USB) connection, which allows users to add or remove peripherals such as a mouse, keyboard, printer, or portable hard drive
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