Musical composition is
- an original piece of music.
- the structure of a musical piece.
- the process of creating a new piece of music.
A piece of music exists in the form of a composition in musical notation or as a single acoustic event (a live performance or recorded track). If composed before being performed, music can be performed from memory, through written musical notation, or through a combination of both. Compositions comprise musical elements, which vary widely from person to person and between cultures. Improvisation is the act of composing during the performance, assembling musical elements spontaneously.
Piece is a, "general, non-technical term [that began to be] applied mainly to instrumental compositions from the 17th century onwards....other than when they are taken individually 'piece' and its equivalents are rarely used of movements in sonatas or symphonies....composers have used all these terms [in their different languages] frequently in compound forms [e.g. Clavierstück]....In vocal music...the term is most frequently used for operatic ensembles..."
Composition as musical form
Main article: Musical form
In discussing the structure or organization of a musical work, the composition of that work is generally called its musical form. These techniques draw a parallel to art's formal elements. Sometimes, the entire form of a piece is through-composed, meaning that each part is different, with no repetition of sections; other forms include strophic, rondo, verse-chorus, or other parts. Some pieces are composed around a set scale, where the compositional technique might be considered the usage of a particular scale. Others are composed during performance (see improvisation), where a variety of techniques are also sometimes used.Some are used from particular songs which are familiar.
Important in tonal musical composition is the scale for the notes used, including the mode and tonic note. In music using twelve tone techniques, the tone row is even more comprehensive a factor than a scale. Similarly, music of the Middle East employs compositions that are rigidly based on a specific mode (maqam) often within improvisational contexts, as does Indian classical music in both the Hindustani and the Carnatic systems, gamelans of Java and Bali, and much music in Africa.
People who practice composition are called composers. Compositional techniques are the methods used to create music. Useful skills in composition include writing musical notation, music theory, instrumentation, and handling musical ensembles (orchestration). Other skills include extended techniques such as improvisation, musical montage, preparing instruments, using non-traditional instruments, and other methods of sound production.
The task of adapting a composition for musical instruments/ensembles, called arranging or orchestrating, may be undertaken by the composer or separately by an arranger based on the composer's core composition. A composition may have multiple arrangements based on such factors as intended audience type and breadth, musical genre or stylistic treatment, recorded or live performance considerations, available musicians and instruments, commercial goals and economic constraints.
Based on such factors, composers or arrangers must decide upon the instrumentation of the original work. Today, the contemporary composer can virtually write for almost any combination of instruments. Some common group settings include music for Full Orchestra (consisting of just about every instrument group), Wind Ensemble (or Concert Band, which consists of larger sections and greater diversity of wind, brass and percussion instruments than are usually found in the orchestra), or a chamber group (a small number of instruments, but at least two). The composer may also choose to write for only one instrument, in which case this is called a solo.
Composers are not limited to writing only for instruments, they may also decide to write for voice (including choral works, operas, and musicals) or percussion instruments or electronic instruments. Alternatively, as is the case with musique concrète, the composer can work with many sounds often not associated with the creation of music, such as typewriters, sirens, and so forth.
In Elizabeth Swados' Listening Out Loud, she explains how a composer must know the full capabilities of each instrument and how they must complement each other, not compete. She gives an example of how in an earlier composition of hers, she had the tuba above the piccolo. This would clearly drown the piccolo out, thus giving it no purpose in the composition. Each instrument chosen to be in a piece must have a reason for being there that adds to what the composer is trying to convey within the work
Recomposition is composition which employs prior material so as to comment upon it such as in mash-ups and various contemporary classical works. It may be thought of as analysis. 
In the US, the copyright symbol is ©, or the letter c inside a circle. The first year the work was published follows the copyright symbol, and the name of the copyright holder thereafter. Copyrights afford the owner of a work control over and exclusive rights to the work. Even though the first US copyright laws did not include musical compositions, they were added as part of the Copyright Act of 1831. Music copyright laws have been revised several times, most notably in the Digital Millennium Copyright Act of 1998 (DMCA). DMCA addressed peer-to-peer music sharing software and other forms of piracy due to new technology such as computer and the internet. A music copyright is often notated as ℗, or a letter P (instead of the letter C) inside a circle. This is because this type of copyright also covers phonorecords, which are physical objects, such as CDs, where the works is contained. A copyright does not guarantee protection from music piracy; however, it prevents other artists from claiming the works as their own.
Copyright, Designs and Patents Act 1988 defines a musical work to mean a work consisting of music exclusive of any words or action intended to be sung, spoken or performed with the music.
In the UK, "music" is normally understood by law to include melody, harmony and rhythm.
- ^ Tilmouth, Michael. 1980. "Piece". The New Grove Dictionary of Music and Musicians, sixth edition, 20 vols., edited by Stanley Sadie, Vol. 14: 735. London: Macmillan Publishers; New York: Grove's Dictionaires. ISBN 1-56159-174-2.
- ^ BaileyShea, Matt (2007). "Mignon: A New Recipe for Analysis and Recomposition", Music Theory Online Volume 13, Number 4, December 2007.
- ^ Sheet music was held to be covered by the term "book" in the Statute of Anne: see Bach v. Longman  but that merely conferred a right to print and reprint the music
- ^ Some countries like Canada have legally defined music as any combination of melody and harmony or either of them, printed or reduced to writing or otherwise graphically reproduced.