Most States of the USA allow citizens to carry concealed weapons (usually a handgun), providing they have a legal permit to do so. This concealed weapon permit is commonly referred to as a CWL, CCL, CWP, or CCP depending on the state. Contrast concealed carry with Open carry.
In "free states" such as Idaho, Wyoming, Montana, Alaska, Arizona the only "permit" required is the Second Amendment. This type of concealled carry is called Constitutional carry.