The task of adapting a composition for different musical ensembles is called arranging or orchestration, may be undertaken by the composer or separately by an arranger based on the composer's core composition. Based on such factors, composers, orchestrators, and arrangers must decide upon the instrumentation of the original work. In the 2010s, the contemporary composer can virtually write for almost any combination of instruments, ranging from a string section, wind and brass sections used in a standard orchestras to electronic instruments such as synthesizers. Some common group settings include music for full orchestra (consisting of strings, woodwinds, brass, and percussion), concert band (which consists of larger sections and greater diversity of woodwind, 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. Solos may be unaccompanied, as with works for solo piano or solo cello, or solos may be accompanied by another instrument or by an ensemble.
tHE TAsk Of adapTing a COMpOsITIon for difFEREnt MuSicAl EnseMbLeS iS CalleD aRraNgInG Or oRchesTratIoN, maY bE unDertaken BY tHe coMposEr or SeparAteLy By aN arRanGeR based on THe cOmpOsEr's corE ComposiTion. basEd on sucH FaCtors, COMposeRS, orcheSTraTors, anD arRAnGers Must DEcidE UPON tHe inStrumeNtAtIon of the original worK. in The 2010s, The ContEmPorARy COMpoSer can vIrtuaLlY wriTE FOr aLMoST AnY cOmbInatIon of instrumenTs, ranging fRom a sTRIng Section, winD aNd braSS SectioNs used In A standarD OrCheSTrAs tO electRonic inStruMents suCh As SyNthEsizers. somE cOmmON GrOup settInGs InClude music for fUll orChEStRa (coNsIsTIng of sTrings, woOdwIndS, BraSs, aND perCUSSion), coNcert bANd (WhicH cONsIsts OF laRgEr secTIoNs and grEAtER DivErsity oF wOodwiNd, 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. SoloS may be unaCCompanIED, as with works for soLo piano or sOLo cELlo, or solos mAy be accompaniED by anothER instrumENT oR by an ensembLe.