Trade secrets include methods, processes, formulas, and other business information, such as customer lists. One example is the process McDonald's uses to cook its French fries. In order for something to be considered a trade secret, the owner must make a reasonable effort to keep the information secret.
Trade secrets, unlike the other types of intellectual property, cannot be registered. There are laws, however, that protect trade secret owners. The main one is the Uniform Trade Secrets Act, which has been adopted in Illinois.
The greatest danger for disclosure of trade secrets is from employees who leave and go to work for a competitor. Most companies require employees who might be in a position to learn trade secrets to sign contracts promising not to disclose the secrets, and the courts generally uphold such agreements.
Those who steal trade secrets can also be prosecuted criminally, under the Economic Espionage Act of 1996.
Trade secrets are valid forever, as long as secrecy is kept. If a trade secret is revealed, it is lost forever.