Exchanges are one of the most popular ways to trade cryptocurrency. A wide range of exchanges exist, each offering slightly different features. Some serve different markets, some are in direct competition, some have cheaper fees, and some are subject to more or less strict regulatory requirements. Most exchanges are centralized, meaning they are operated by a single company, which may be obliged by the laws of the jurisdiction in which it operates to collect data on its customers. Others are decentralized, but as a result have higher escrow requirements since you are dealing peer-to-peer instead of with a trusted entity. Exchanges can be broadly broken down into two categories: exchanges which accept national currency (fiat money) and exchanges which deal in cryptocurrencies only.
Instant exchanges perform a similar function to normal exchanges, but without the requirement to log in. They effectively convert one currency to another, with some limits on the amount to be exchanged and usually at a less advantageous rate. Others may even offer to sell cryptocurrency as a credit card purchase.
A number of sites have appeared to facilitate trading of PCOIN between individuals. Volume is often lower, and users typically make offers or requests at the price they are willing to pay, and wait for someone to contact them and arrange details of the sale. More advanced peer-to-peer sites offer escrow services for a fee to prevent cheating during the sale between two parties who have never met.