There are several different types of Pin presented on the Raspberry Pi 40 pin connector.
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The important thing to know is that there are two voltages present on a raspberry pi and genuine damage can be done to the device if this is ignored.
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One of the corner pins is +5Volts and this is the voltage supplied by the USB Power connector this MUST Not be connected to any of the other pins. they live off 3.3Volts and this should be honoured.