What do you mean by vector interrupt? Explain.

A vector interrupt is an interrupt in which the interrupting device itself supplies the address, or a vector number, of its service routine. The CPU uses this vector to look up the starting address of the routine in the interrupt vector table.

So the CPU does not have to poll all devices to find the source. This makes the response fast. For example, in the 8086 each interrupt type number n points to the table entry at address $4n$. Daisy chain priority hardware is often used to send the vector from the highest priority device.