Boiler room describes an operation in which high‑pressure, often misleading sales tactics are used (usually by telephone or online) to induce investors to buy worthless or high‑risk investments, frequently involving shares, bonds, carbon credits, cryptoassets or other speculative products. The term is descriptive rather than a defined statutory concept in the UK or Ireland, but such schemes typically involve investment fraud, market abuse, unauthorised investment business and breaches of financial promotions rules. In England and Wales, Scotland and Northern Ireland, boiler room activity commonly engages offences under the Financial Services and Markets Act 2000, the Fraud Act 2006 and related regulatory regimes enforced by the Financial Conduct Authority and criminal authorities. In Ireland, similar conduct may breach the Investment Intermediaries Act 1995, the Criminal Justice (Theft and Fraud Offences) Act 2001 and Central Bank rules on authorised investment firms and investment advice. For legal practitioners, the concept is relevant in advising on financial services regulation, cross‑border enforcement, asset recovery, investor redress, director disqualification and professional negligence claims arising from failure to detect or warn about boiler room scams. Usage is broadly consistent across all four jurisdictions.