Conceptually, pump and dump is very simple: it's promoting a traded product with the intent that it's price will rise. The fraudster buys the product, "pumps" it, then when the price has risen "dumps" it which almost invariably causes the stock to fall, resulting in losses for those that bought as the price rose.

For many years, stock manipulation, on a smaller scale, was done by "financial" journalists who would get tips from people working in companies about news for the next day. During the embargo period they would buy shares in the company then sell them when the price rose. That's usually classed as insider trading rather than pump and dump.

"Pump and Dump" usually refers to mass market communications, be it emails, social media influencing or broadcast advertising designed to move a market in a very short time. Often the target is a company with an extremely low share price, perhaps even fractions of a US cent. In this way, a small price movement is a large percentage change.

Usually, it's in a share that has a very small market, perhaps only via a single market maker. There may be very few shares in the open market, if any. So the price is not entirely set by demand.

It doesn't matter what the product is: if enough people can be persuaded that they must jump aboard or they will lose a great opportunity, prices will rise. Take bitcoin as an example. Or for that matter, any traded currency.

Pump and Dump is not the same as a Ponzi scheme. Those that say that the inflation of e.g. bitcoin is a Ponzi scheme do not understand what a Ponzi scheme is.

Across the Crypto-world, there have been convictions for promoting currencies which have later collapsed in value exposing those who relied on representations of celebrities, for example.