The term “Chart” has a few synonyms, such as “File”, “Map”, or “Simfile”. A chart contains the notes that go to the audio file presented along with it.
The most recommended program is ArrowVortex, a free editor with a graphical interface. One may also choose DDReamStudio, an older alternative. The ingame editor, available in other forks of StepMania 5, was deleted from Etterna to encourage users to chart with external software, which is more advanced and offers more possibilities.