In the common law legal system, an indictment is a formal charge of having committed a serious criminal offense. In those jurisdictions which retain the concept of a felony, the serious crime offence would be a felony; those jurisdictions which have abolished the concept of a felony often substitute instead the concept of an indictable offence, i.e. an offence which requires an indictment. Traditionally an indictment was handed down by a grand jury, but most common law jurisdictions (with the exception of those in the United States) have abolished grand juries.
In Australia, an indictment is issued by government official (the Attorney-General, the Director of Public Prosecutions, or one of their subordinates). A magistrate then holds a committal hearing, which decides whether the evidence is serious enough to commit the person to trial.
In cases where there is a trial, indictable offences are normally tried by jury, unless the accused waives the right to a jury trial. However, the vast majority of cases in the United States are settled via a plea bargain. The accused is not normally in common law systems entitled to a jury trial if the offence with which they have been charged does not require an indictment; the main exception here is that jurisdictions in the United States grant the right to a jury trial for most criminal offences.