Definition & Meaning of "free lunch"

What is the origin of the idiom "free lunch" and when to use it?

The idiom "free lunch" has its origin in the practice of offering complimentary meals to patrons at bars or taverns, often as an incentive to attract customers. This tradition, prevalent in the United States during the late 19th and early 20th centuries, gave rise to the saying "there is no such thing as a free lunch." While the initial intention was to entice customers with free food, the phrase evolved into a metaphorical expression cautioning that nothing comes without a cost or hidden consequences. It is used as a reminder that even seemingly generous offers may involve trade-offs or obligations.