Middle C
From “Middle C¨ in Music Theory for Electronic Music Producers
In addition to the letter name C, there is a number. That number indications[sic] which C we are looking at. On a keyboard (depending on the size of the keyboard), we might have six or seven different C keys. […] Middle C is the C key that is right in the middle of the keyboard. Technically speaking, middle C is C4.
Simply spoken, conventionally, middle C is C4. To know how to find C more generally, refer to 20240901115917-Locating_C_Piano_Key.
Caution
There can be “some confusion¨ in finding C4 as smaller keyboards wherein the musical alphabet and its accidentals repeat only once or twice can have buttons that allow us to shift the auditory frequencies produced by those keys down or up (Allen 2018, 31). (However typically the default has C4 as the either at the beginning or start of that small keyboard.) Furthermore, confusion is exacerbated by “synthesizer manufacturers about middle C¨ as some “label middle C as C3¨ (Ibid).
Reference image:

music music_theory Western piano classical C4 middle_C C3 musical_alphabet
bibliography
- “Middle C.” In Music Theory for Electronic Music Producers: The Producer’s Guide to Harmony, Chord Progressions, and Song Structure in the MIDI Grid., 1st ed., 31. Minneapolis, MN: Slam Academy, 2018.