Key signatures
Key signatures are the markings that show the current key of music by indicating which notes in the scale for that key are sharpened or flattened. They are shown at the start of each system on every applicable staff.
Using key signatures saves space, as by indicating which notes are generally going to be sharp or flat in the music in one group at the start of each system, these notes do not need an accidental beside them every time they occur.
By default, key signatures apply to the whole score. However, there are certain situations where some parts require their own key signature, independently of the rest of the ensemble. You can input key signatures that apply to all staves or only apply to single staves in Dorico.
Traditionally, accidentals are organized following the pattern of the circle of fifths, which is different for sharp keys and flat keys.
In Dorico, key signatures exist within the overarching tonality system for your project. The two tonality systems that come as standard in Dorico are 12-EDO and 24-EDO.
Once you have selected or created a tonality system for your project, you can create custom key signatures and custom accidentals within that tonality system.