This has become a generic name for a scam that generally involves an appeal from a foreign citizen, usually posing as a dignitary of some third-world country. These letters, facsimiles, and e-mails usually inform the recipient that the dignitary is allegedly due a large sum of money and will need assistance in receiving it. The request usually suggests involving the recipient in some form of illegal money laundering.
The recipient is promised a large portion of the money. If they respond to the request they will either will be asked to provide money as "processing fees" or personal financial information to facilitate the transaction. Any money wire transferred to the scammer will be nearly impossible to recover. Any personal information provided will likely be used to commit identity theft.
If you believe you have been victimized by a scam or wish to report suspicious activity, please file a report here.