A halt in trading refers to a temporary cessation of buying and selling of securities listed by a company. This can be initiated by the stock exchange, its agent, or requested by the company itself. Typically, a trading halt occurs when an issuer needs to make a significant public announcement, but it can also be imposed if the issuer is not meeting exchange requirements or if it is in the public interest. It is a powerful tool used to ensure fair and transparent trading practices in the market.