G major (or the key of G) is a major scale based on G, with the pitches G, A, B, C, D, E, and F♯. Its key signature has one sharp, F♯; in treble-clef key signatures, the sharp-symbol for F is usually placed on the first line from the top, though in some Baroque music it is placed on the first space from the bottom (the F one octave below).
In the Baroque era, G major was regarded as the "key of benediction".
Of Domenico Scarlatti's 555 keyboard sonatas, G major is the home key for 69 (12.4%, about 50% more than the 8.3% one would expect in an even distribution). It bears noting that this over-representation of the key may be at least partially the result of G major's proximity to other keys (such as D major and C major) widely used by a variety of composers for solo keyboard and for keyboard with strings, given that the meantone tuning systems common in Scarlatti's day made some keys more appropriate than others for a given instrument setting.
Twelve of Joseph Haydn's 104 Symphonies (11.5%, 1.4 times more than in an even distribution) are in G major. Likewise one of Haydn's most famous Piano Trios (with the Gypsy Rondo), and one of his last two complete published string quartets (from opus 77), among others.
G major is the home key of Mozart's Eine kleine Nachtmusik, serving as the tonic for three of its four movements (the exception being the second movement, titled Romanze and set in C major). However, almost none of his large-scale works such as his symphonies or concerti are in this key; the only exceptions are the Piano Concerto No. 17, Flute Concerto No. 1 and his String Quartet No.14, along with some examples among his juvenilia (works written in his youth before his maturity as a composer).
G, sometimes called the 'people's key', is one of the most frequently-employed keys across classical and popular music. This is in part because of its relative ease of playing on both keyboard and string instruments: its scale comprises only one black note on the keyboard, all of a guitar's six strings can be played open in G, half of the strings on the mandolin and violin/fiddle are in the G chord when open, and the banjo is usually tuned to open G. It is the key stipulated by Queen Elizabeth II to be used for "God Save the Queen" in Canada. The music to the American national anthem, The Star-Spangled Banner, was originally written in G major. Though it is now usually sung in A-flat or B-flat major, some people, most notably humorist and commentator Garrison Keillor, are campaigning to return the song to its original key; they argue that the song is already very difficult to sing on account of its range (one and a half octaves), and the modern standard key makes it still more difficult.