A deadly weapon is any object or thing that can be used to cause the death of a person. Guns and knives are examples of deadly weapons. There are also many things that people may not immediately suspect as deadly weapons, but still can qualify. Examples of some of these things include baseball bats, golf clubs, wrenches, screwdrivers, and even cars.
A deadly weapon is basically an item that can be used to kill. Firearms in particular are considered a very dangerous deadly weapon; and there are both federal and state laws which regulate their use. The concealed carrying of firearms on one's person is especially regulated. For example, states frequently prohibit a person who has committed any felony, or any person who has been committed to a mental institute to treat a mental illness from carrying concealed firearms. This is to try to prevent unnecessary deaths or violent crimes from happening.