I/O plate
Also called I/O shield, I/O template, the Input/Output plate (I/O plate) is a thin removable metal plate that protects the back of a computer and gives access to I/O devices like USB (Universal Serial Bus). Every new computer case includes one or more generic I/O plates, however, when building a computer, these are often replaced by the one included with the motherboard.
In the example above, all holes are punched of the I/O plate, but some cases and motherboards do not come this way. If your I/O plate does not have a hole pre-punched for your motherboard, make sure to punch them out with a screwdriver before installation. Also, make sure the holes match your motherboard back pannel.
The I/O plate should not be confused with the expansion slot cover.