There are several different combinations that can be used, and they are not always the same, but the most commonly found in the US would be a black wire (LIVE) and a white wire (NEUTRAL).
You can see different combinations as well, not just black and white, here are a few:
BLUE/RED: The red wire is typically LIVE, and the blue is NEUTRAL.
BLACK/BROWN: The brown wire is typically LIVE, and the black is NEUTRAL.
BROWN/BLUE: The brown wire is typically LIVE, and the blue is NEUTRAL.
GREEN WIRE: Some fixtures will have a green wire present, and that is the GROUND wire. If you do not see a GROUND wire on your fixture, the fixture itself is already grounded.
PURPLE/GRAY: Purple and gray wires means that the fixture can be used with a dimmer. Those wires are intended to be connected to a dimmer switch, if you are not going to be using them you are able to cap them off individually with a wire nut.
If you are not sure which wire is neutral or live, please use a voltmeter to be 100% certain.