Music can usually be input by using the mouse and computer keyboard, although some scorewriters will also allow input to be played to them from a MIDI keyboard. As scorewriters tend to use their own unique file formats for storing music, many will include utilities to translate from foreign formats, or MIDI files, to their own. Also a few will allow input by scanning scores using musical OCR software.
The output of scorewriters can usually be fine tuned, either by dragging graphical objects around in a GUI or by adding parameters to text-based input files.
Most scorewriters also allow the music to be played back via MIDI. This means that scorewriters have a certain amount in common with sequencers (many of which can also write music notation up to a point), though scorewriters are used primarily for writing notation and sequencers primarily for recording and playing music.
A few scorewriters allow users to publish scores on the Internet using their own formats, thus making them accessible only to other users of the same program. However more allow the exporting of the score to a PDF file for distributing the score and MIDI for distributing the music. More recently there have been Flash-based scorewriters developed that allow distribution and advanced interaction of sheet music online to any user with a modern browser.
MIDI files are often used as a form of 'workaround', because almost all scorewriters can open and/or save them. However, the MIDI file format is designed for representing playback rather than notation, so it only produces approximate results and much notational information is lost in the process.
Sibelius 4 is capable of opening Finale's .MUS files in a limited form as well as its ENIGMA Transportable Files (.ETF). Both Finale and Sibelius support MusicXML files to varying degrees.