An orchestra is a large instrumental ensemble typical of classical music, which mixes instruments from different families, including bowed string instruments such as violin, viola, cello and double bass, as well as brass, woodwinds, and percussion instruments, each grouped in sections. Other instruments such as the piano and celesta may sometimes appear in a fifth keyboard section or may stand alone, as may the concert harp and, for performances of some modern compositions, electronic instruments. The term orchestra derives from the Greek ὀρχήστρα (orchestra), the name for the area in front of a stage in ancient Greek theatre reserved for the Greek chorus. A full-size orchestra may sometimes be called a symphony orchestra or philharmonic orchestra. The actual number of musicians employed in a given performance may vary from seventy to over one hundred musicians, depending on the work being played and the size of the venue. The term chamber orchestra (sometimes concert orchestra) usually refers to smaller-sized ensembles of about fifty musicians or fewer.
The instruments included in the modern orchestra are the following:
Woodwinds
Brass
Strings
Keyboards
Percussion
Other
-As required by the compositions in the program, various electric instruments or electronic instruments may be used in the orchestra. These performers are not typically permanent orchestra members. They are typically freelancers hired on contract for one or more concerts. Instruments may include:
In the United States, the late 20th century saw a crisis of funding and support for orchestras. The size and cost of a symphony orchestra, compared to the size of the base of supporters, became an issue that struck at the core of the institution. Few orchestras could fill auditoriums, and the time-honored season-subscription system became increasingly anachronistic, as more and more listeners would buy tickets on an ad hoc basis for individual events. Orchestral endowments and—more centrally to the daily operation of American orchestras—orchestral donors have seen investment portfolios shrink or produce lower yields, reducing the ability of donors to contribute; further, there has been a trend toward donors finding other social causes more compelling. Also, while government funding is less central to American than European orchestras, cuts in such funding are still significant for American ensembles. Finally, the drastic falling-off of revenues from recording, tied to no small extent to changes in the recording industry itself, began a period of change that has yet to reach its conclusion.
A little help from: https://en.wikipedia.org/wiki/Orchestra#Instrumental_technology