What is a Boiler Room?

In literal terms, a boiler room is a space where salespeople make unsolicited calls to a wide range of potential investors to convince them to buy highly-speculative, fraudulent or even nonexistent securities. (I said "in literal terms" because the salespeople do not need to be in the same room...)

These salespeople usually transmit solely positive information about the investment, make false promises of high returns and lie about the investment risks. Simultaneously, they resource to aggressive selling techniques, such as stating that it is an unique opportunity that has to be seized immediately, or that otherwise will be lost.

Note that this practice is often executed within a pump and dump scheme, as the manipulators try to convince potential investors to buy a worthless security - with such purchases pumping the price up, to then dump the securities at a high price.