Crimes are often classified in terms of their seriousness as felonies and misdemeanors. An act may be a felony in one state and a misdemeanor in another.
Felonies include serious crimes such as arson, murder and robbery, for example. Crimes not classified as treason or felonies are misdemeanors and include such things as reckless driving and disturbing the peace.
In most crimes, motive or intent to commit the crime is not a necessary element. All that is necessary is that the defendant voluntarily did the act that the law defines as a crime. Something can be a crime even if the wrongdoer has no knowledge that a law has been broken.
Generally, when one thinks of a crime, he thinks of an act which causes harm to another person. However, there are many crimes that are committed without harm to others. For example, a person may be guilty of speeding or reckless driving even though no one is hurt. In such a case, society has decided that such an action should be prohibited because of its potential to harm others.