A guitalele is a guitar-ukulele hybrid, that is, "a 1/4 size" guitar, a cross between a classical guitar

Classical guitar

The classical guitar is a 6-stringed plucked string instrument from the family of instruments called chordophones...

 and a tenor ukulele

Ukulele

The ukulele, ; from ; it is a subset of the guitar family of instruments, generally with four nylon or gut strings or four courses of strings....

. The guitalele combines the portability of a ukulele, due to its small size, with the six single strings and resultant chord possibilities of a classical guitar. It may include a built-in microphone that permits playing the guitalele either as an acoustic guitar

Acoustic guitar

An acoustic guitar is a guitar that uses only an acoustic sound board. The air in this cavity resonates with the vibrational modes of the string and at low frequencies, which depend on the size of the box, the chamber acts like a Helmholtz resonator, increasing or decreasing the volume of the sound...

 or connected to an amplifier. The guitalele is variously marketed (and used ) as a travel guitar or children's guitar. In January 1997, Yamaha Corporation came out with the GL-1 Guitalele

GL-1 Guitalele

The Yamaha GL-1 is a guitalele, also known as a 1/4 size guitar or guitar-ukulele hybrid, combining the size of an ukulele with the wider fretboard and six single nylon strings of a classical guitar....

.

A guitalele is the size of a ukulele, and is played like a bass pitched up to “A” (that is, up a 4th, or like a guitar with a capo on the fifth fret).
This gives it tuning of ADGCEA, with the top four strings tuned like a low G ukulele.