Prosecutors in some states have the option of filing felony charges through an indictment rather than a complaint, which typically requires a preliminary hearing in front of a judge. (After the preliminary hearing in many states, the complaint gives way to an "information) In federal court, felonies typically proceed through the grand jury process.
In both the state and federal systems, if the grand jury finds sufficient evidence of criminal behavior, it returns an indictment. Both an indictment and a typical information signify a determination by a neutral third party (grand jury or judge) that there is a factual basis for criminal charges. The next major step, short of a plea deal or dismissal, is likely trial.