Prominences are H-Alpha emission features projecting beyond the limb of the sun, consisting of complex clouds or streamers of gas above or within the chromosphere. They generally come in two broad classes: Active (limb flares, surges, sprays, loops), and Quiescent (quiet region filaments, active region filaments). Filaments are merely prominences seen in absorption against the disk of the sun, so the terms have been used somewhat interchangeably. To be perfectly correct, a filament cannot be a prominence unless it sticks up over the limb. Solar flares frequently produce some sort of active prominence which is generally visible in H-alpha on the limb and sometimes (with a sub-angstrom filter) on the disk. These active prominences are most often "surges" and "sprays". A surge is a jet of gas like the stream from a garden hose, while a spray is where material goes off in a variety of directions.