Charging documents relate to the government's formal charges against an individual for a crime. There are a number of different types of charging documents including indictments, complaints, citations, or information. Let's examine two of the more common and significant ones.
In the United States, an indictment is used by the federal government, as well as several states, to formally charge someone with a crime. In fact, the Fifth Amendment requires that a grand jury issue an indictment before anyone can be officially charged with "a capital, or otherwise infamous crime." When a grand jury issues an indictment, the defendant is then arraigned. This triggers the first part of a criminal trial in which the defendant offers their plea. The significance of an indictment is that they are usually reserved by the states for very serious crimes or by the federal government and that the information has been reviewed by a grand jury.
Another type of charging document is an information. The 14th Amendment has not incorporated the part of the 5th Amendment pertaining to grand juries into state laws. Therefore, when states charge someone with a crime, they do not need to issue a grand jury indictment. (However, someone charged with a federal crime has the option to waive a federal indictment as part of a guilty plea and be issued an information instead.) When a state makes a charge, they often issue an information, which does not require a grand jury. Instead, a judge or magistrate fills that role. Someone charged by an information often has the right to challenge these charges at a preliminary hearing. The prosecution must then convince the presiding judge that they have sufficient probable cause to go to trial.