In music, transcription is the act of notating a piece of music or a sound which was not previously notated. Some notable composers do not read or write music, and it is up to a music transcriber to transfer the musical ideas into a printed form. Transcription has also come to mean arranging a piece of music which was originally written for one instrument or group of instruments so that it may be performed on a different instrument or group of instruments; this is an 'arrangement'.

Music engraving is the art of drawing music notation at high quality. The term music copying is almost equivalent, though music engraving implies a higher degree of skill and quality. Plate engraving, the process engraving derives from, became obsolete around 1990. The term engraving is now used to refer to any high-quality method of drawing music notation, particularly on a computer.

Music orchestrators prepare music for performance by musicians.
 

The simplest task that I do is when I am given a manuscript of handwritten music by a composer and have to prepare this for publication and performance, using computer music software and producing accurate printable scores and instrumental parts. 

However, frequently, the composer only writes the theme or tune, and the arranger or transcriber then fills in the rest of the music. It takes decades of experience to learn how to do this well, as different instruments will change the mood of the music radically. Not only does the arranger have to choose which instruments should be used, but an extensive knowledge of the range of each instrument needs to be known. It is no use writing notes for a clarinet if the pitch is too low for the clarinettist to play. In addition, some instruments play music transposed into different keys to accommodate their instruments.

Sometimes a composer will write just a short theme. The arranger then extends the tune into a much longer piece of music, by adding sections that will compliment the music. The arranger at this point becomes a composer in his or her own right.  

An orchestrator takes the composed theme and produces a score and parts for the entire orchestra, from the violins and the rest of the string section, through the wind instruments, brass, percussion and keyboard. It is vital that the orchestrator knows the composer’s intent for the piece, what the mood should be, and who is playing it.  This is a very difficult task. The orchestrator has to decide which instruments should be playing at different points in the music. The music changes according to which instruments are playing.