If you had an email account in the 1990s, you were personally selected to help a Nigerian prince recover his rightfully due inheritance. He may have written to you many times, pleading with you for your help and thanking you profusely in advance for your generosity and kindness. Some of us got emails from different princes or members of African royalty who had been forced to flee their countries. The English was broken, but the message was clear – we were special, we had been chosen to help, and in return, we were going to be rich beyond our wildest dreams. We were victims of an attempted scam.
The basic idea behind the scam was that an extremely wealthy person in Nigeria had his accounts frozen or could not transfer money out of the country without help. The scammer either requested that money be sent or that bank account numbers be sent to facilitate the transfer of the scammer's assets for which the person would be rewarded handsomely later.
That this was a scam seems obvious, as why would some wealthy African need the assistance of random Americans? However, everyone knows about the scam because it worked. The scammer just needs one person out of millions to take the bait. That is true with most common scams. Only one person needs to take the bait to make attempting to scam thousands worth the scammer's time.