A warning label is a label attached to an item, or contained in an item's instruction manual, warning the user about risks associated with the use of the item, and may include restrictions by the manufacturer or seller on certain uses. Most of them are placed to limit civil liability in lawsuits against the item's manufacturer or seller. That sometimes results in labels which for some people seem to state the obvious.
In the United States warning labels were instituted under the Federal Food, Drug, and Cosmetic Act of 1938. Cigarettes were not required to have warning labels in the United States until in 1965 Congress passed the Federal Cigarette Labeling and Advertising Act (FCLAA).
Warning labels have been produced for different items. In some cases, these labels warn against some very strange occurrences such as the legendary microwave warning that states 'do not dry pets in microwave'.
Some companies hold 'strange warning label competitions' such as the former M-law wacky warning labels competition.
While many products intended for human consumption may require warning labels due to the health risks associated with using them, it is only tobacco products that have strongly worded warnings on their health risks.