The dallas 1-wire bus is made up of either 2 or 3 wires with the sensors attached along the bus. One bus wire is ground and one is the data line. The third (optional) wire is to carry a full 5V to the devices. Since the data bus uses a pullup resistor, power can be sourced from the bus by the device. If you ground the normally 5V supply pin on the device, it will draw power from the data line.
Since the data line on the bus has a pullup on it, only a limited amount of current can be supplied to the device. This is fine until the device needs to execute a CONVERT command to sample the temp and measure it. This requires more current than can be drawn thru the data line. So back at the head end of the bus (where the microcontroller is) after issuing a CONVERT command enables full power to the data line by bypassing the pullup resistor. The device can then draw as much current as it needs. After the CONVERT command is finished, the microcontroller disables the pullup bypass so that communications can take place on the data line. This saves running the 5V power wire to each device.
I don't know what you mean about many wires, all devices can reside on one bus. Please just download the document, it explains it all much better.