groundfungus:
The input is "pulled" HIGH by the internal (or external) resistor) while the switch is open, therefore is a 1 (or HIGH or true). When the button is closed, the input is "pulled" to ground for a 0 (or LOW or false). The switch is said to be "active low".
Hi, thanks for the quick anwser, I think I get it now. This kind of swich is open while I'm pressing the button, right? and when I release the button the circuit is closed?