Laws to register guns are state laws; therefore the laws will vary depending on the state itself. Laws to register guns are not created for all states, meaning some states do not require guns to be registered. For those that do have a system of law to register guns, they generally are created for the same reason, to protect the citizens of the state as well as avoid any possible harm that can be done.
Laws to register guns vary greatly; however some common laws to register guns include: providing detailed information about where a person bought the gun, having a gun license, being of a certain age, and reason or intended use of the gun (such as hunting, or protection). A complete list of gun laws for each particular state can be found in State Laws.