The site below has thorough explanations.
http://kropla.com/electric.htm

The same site also has a table for describing electrical systems worldwide.
http://kropla.com/electric2.htm

However, for those like myself that prefer concise writeups, here's a brief summary that should be sufficient to help prepare for your trip. Note that this message is intended for US residents, if you are from somewhere else, you'll need to read more carefully and check the table to use this information.

Your three primary considerations are:
A) Voltage(V) provided in the country you are traveling to (you can check the table)
B) Frequency(Hz) provided in the country you are traveling to (you can check the table)
C) Adaptors for the type of outlet(s) you will find (outlets are those things in the wall you plug your stuff into)

If the voltage in the destination country is between 110 and 120V, then you do not need to worry about A)Voltage. If the voltage is higher, you should do an inventory of all electronics you plan to plug in. Check the equipment and/or power line for the voltage and frequency specs. Many cellphones, PDA's, laptops, and other relatively newer equipment should be labeled with something like "INPUT: AC 100V-240V~ 1.0A 50/60 Hz", meaning anything in the voltage range of 100V-240V and frequency range of 50Hz-60Hz is acceptable. If you have any equipment that says something like 120V 60Hz, you will need to use a transformer. You might be able to purchase one in the country you are traveling to, but to be safe, purchase one in advance and get a good one. You don't want to ruin your electronics because of a cheap transformer. If you are using this for electronic equipment, make sure you purchase a transformer and not a converter.

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quote:

http://www.laptoptravel.com/Article.aspx?ID=339
First, is your device an electric appliance with a high power heating element or mechanical motor such as a hair dryer or iron? If you are using an electric appliance, you need a converter. Or is your device electronic, using electronic chips or circuits, such as a computer, printer or VCR? If you are using an electronic device, you need a transformer. When in doubt about the type of device, use a transformer. Both Electric appliances and electronic devices work with a transformer, but only electric appliances work with a converter.

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"However, for those like myself that prefer concise writeups, here's a brief summary that should be sufficient to help prepare for your trip."

Let me break it down farther for you:

Make sure EVERYTHING you are going to plug into a wall says:

100-240v
50-60Hz

This should cover you for ALL the places you're planning on going in the world.

As for adapters - you can buy sets here that cost a fortune or buy one overseas for $1-2 (never been disappointed with my dollar adapters). I bring a small extention cord with 3 outlets on the end so I only need one adapter to produce multiple outlets.

If you feel the need to travel with hairdryers and such, many hotels have hairdryers and other devices are cheap in most Asian countries.

Now, from a traveling man's PoV you should make sure your camera, laptop and any other piece of technology you use conforms to the standard mentioned above. If it does not, shop around for one that does. If you are a man bringing curling irons and hair dryers with you on your vacation you got bigger problems then anything that should be discussed here.

E

Also, make sure you have some means of going from a three prong (your power strip/surge suppressor) to a two prong as I am yet to see a three pronged outlet anywhere in Thailand. It may just be my bad luck, but better safe than sorry. If you have one of those little adapters that has the same depth as the ground prong, you should be okay.

Thanks for posting this info, guys, and for breaking it down for a DOLT like me when it comes to such stuff. To say the least I had some ‘issues’ with plugging in my laptop at two hotels in the Philippines, despite the AC power brick meeting all the specs listed above as supposedly being ready for use ‘anywhere’. After plugging my grounded 3-prong plug into the trusty dollar (30 pesos) adapter and then plugging it into ANY of the electrical outlets (230v???) at Apartelle Royal, there was an audible POP that made me not want to actually try and connect my laptop. The same thing happened at Central Park when I used the outlet labeled ‘220’. Central Park has an outlet labeled ‘110’, however, and I used this and everything worked fine.

Indonesia sure had some funky looking electrical outlets, and a quick glance at Carrefour didn’t turn up a promising looking adaptor.

BTW, China Airlines has AC power available in Coach, and they use a US standard 3-prong electrical outlet.

I had a transformer blowed up on me in Indonesia. It was also a super chepo especial version that was clearly labeled 110-230v 50-60hz so it should have been fine. I plugged it in in the bathroom in a ground fault protected socket and it hummed a little and then the socket went dead. Being the genius I am, I said "hmmmm this fault protected socket stopped working for some reason, I guess I'll plug it in someplace else". I got out my trusty giant three prong Singapore adapter and plugged that puppy in out in the bedroom where it instantly detonated in my hand with a resounding blast that took out the power to the entire floor of the hotel. I was now standing in the dark doing an inventory of my fingers but all were still accounted for. My cell phone was attached when I plugged it in but was unharmed by the power surge or the blast. Me now thinks the generic super chepo transformers are not always labeled correctly. Never any problems with branded transformers or oem ones that come with hardware.

Sancho--I am amazed you found a GFI-protected receptacle in Indonesia.

Porker--I also got that popping sound, due to poor design and 220 volts, whenever I plugged anything in, and not just in Indonesia or the Philippines. But I tried to complete the electrical connection quickly to avoid potential arc damage to my plug, and so far, so good. In many cases, my equipment plug was plugged into an adapter, mostly with the round prongs.

Staples sells an adaptor that allows a US triple prong device ( a laptop charger, for example) to be plugged into any foreign outlet. It is a single adaptor with multiple modes, sells for about $19, but I think it is ingenious.