Different countries use power supplies at different voltages (usually 110V or 220-240V) and AC frequencies (usually 50 Hz or 60 Hz). Your computer should work with a different country's power supply as long as you have an appropriate power adapter. You may also need to flip a switch.

If you have a laptop, all you should need to do is get the right plug for your power adapter. Some laptops come packaged with more than one plug for their adapter, so you may already have the right one. If not, plugging your existing one into a standard travel adapter will suffice.

If you have a desktop computer, you can also get a cable with a different plug, or use a travel adapter. In this case, however, you may need to change the voltage switch on the computer's power supply, if there is one. Many computers don't have a switch like this, and will happily work with either voltage. Look at the back of the computer and find the socket that the power cable plugs into. Somewhere nearby, there may be a small switch marked "110V" or "230V" (for example). Switch it if you need to.