People who are not familiar with consumer eletronics may get confused with the power adatpors easily. No worry, it is easy to understand, read this article and you should know everything about power adaptor.
Input is something related to the power supply system in your country. Most of the countries are using 220V or 240V power supply system. But some use 110V power supply system (United States and Japan). If the power adaptor marks as 220V input only, you can't use it in 110V countries like Japan. Nowadays, most of the power adaptors are using input 110V-240V. In other words, these adaptors work worldwide.
Output indicates how strong the power current. If you use a 2000mAh power adaptor (quite strong) to charge a simple mp3 player, it may cause your mp3 player burn the parts. However, if you use a 300mAh power adaptor (quite low) to charge a HD PMP, full recharge may take up to 24 hours or more. 1000mAh is moderate for most handheld eletronics items. Handheld devices require 5V output, laptops require 18V output. All the power adaptors in our shop should be around 5V.
Using Computer USB Port
Now it is very common that manfucturers do not supply power adaptor but instructs you to charge the deivce via computer USB port. A computer USB port usually has output of 500mAh.