On electronic schematic diagrams, the 555 timer circuit is usually depicted with supply voltage facing upwards, ground voltage facing downwards, inputs on the left and output on the right. The pin numbers do not necessarily correspond to their physical placement on any 555 timer chip.
The most common schematic depiction of a 555 timer circuit begins with the first grounding pin at the lower left corner of a square, facing downwards. To its left is the second pin, the trigger pin that starts the 555 timer's electric activity. Moving clockwise around the schematic, the next pin is the sixth pin. This is the threshold pin that monitors voltage on the discharge pin, which immediately follows.
Moving further clockwise around the chip, the first upward-facing pin is the fourth pin, the pin that resets the 555's timer. Both this pin and the pin next to it, the voltage pin, need to be connected to the supply voltage for the 555 circuit to function. Adjacent to these pins, on the right side of the diagram, is the output pin through which high or low voltages travel, according to the operation of the 555's timing operation as determined by how the other pins are connected.