A chart is a set of notes that go to the audio file presented along with it. The term “Chart” has a few other words close in meaning, such as “File”, “Map”, or “Simfile”. While they are sometimes used interchangeably, their meanings are a little different - by definition, “File” and “Simfile” refer to a group of charts for one song. “Map” implies it's an osu!mania chart.