Most visitors to Cambodia will need a visa. You can obtain one in advance from a Cambodian embassy or consulate, or you can apply for one on arrival in Seam Reap or Phnom Penh. Most people opt for the visa on arrival, so the queues to get the visa can be quite long.
To obtain a visa on arrival, you'll need to complete an application form and attach a passport photo of yourself to the application. Your passport will need at least one full blank page to paste the visa into, and your passport will usually need to be valid for at least six more months from your date of arrival. The fee for most visa types is US$ 20.
You can also apply for a Cambodian visa online. It takes three days to process the e-visa and you will need a digital passport photo of yourself.
The currency of Cambodia is the Riel, although US Dollars is used at most places frequented by tourists and can be used interchangeably for Riel just about everywhere else. While the Riel is theoretically convertible, it isn't commonly traded. One Dollar is worth
There are currency exchanges throughout the major tourist destinations, but changing money is more or less unnecessary if you're carrying US notes in small denominations. Automated Teller Machines (ATM) have recently appeared on the scene, although still relatively uncommon. You'll find them in most tourist areas if you look hard enough.
Electrical current in Cambodia is 220 volts, 50 cycles. Electrical sockets take two flat prongs. The power supply is relatively stable in the big cities, although the power supply is somewhat "dirty" (inconsistent in voltage). Outages can be frequent in the rainy season.