pull-up resistor
A pullup resistor is used to raise the input level of electronic circuits with a DC voltage level. Such a pull-up resistor is connected to the operating voltage and biases the input of an active circuit or a logic circuit with this voltage. In a sense, it raises the input level to the operating voltage level.
The control of such a biased logic is done by switching the input to ground potential via a transistor or a switch. In this case, the pullup resistor loses its function, which it does not perform again until the switching function is interrupted or the switch is open.
Logic gates can be constructed with pullup or pulldown resistors that perform the complementary function.