Steven Siro Vai (; born June 6, 1960) is an American guitarist, composer, singer, songwriter, and producer. He was voted the "10th Greatest Guitarist" by Guitar World magazine, and has sold over 15 million records. A three-time Grammy Award winner and fifteen-time nominee, Vai started his music career in 1978 at the age of 18 as a transcriptionist for Frank Zappa, and joined his band from 1980 to 1983. He embarked on a solo career in 1983 and has released eight solo albums to date.

Vai designed the Ibanez JEM guitar, a unique instrument that incorporated a series of groundbreaking designs that have since become staples in feature throughout the guitar industry, in 1985. In speaking of the development of the guitar, Vai says, "Stratocasters had whammy bars--which were fantastic--but they were very limited, were always going out of tune, and had single-coil pickups. Les Pauls had humbuckers--which gave you that real scream in the bridge position--but no whammy bar, and I didn't like the way they sat. Neither guitar had twenty-four frets. So I went to a guitar shop in Hollywood, where I had these elements implemented into a guitar (what would have been considered a Superstrat at the time). The guitar was designed with a sharper body shape, a large cutaway around the neck, twenty-four frets, a fully floating tremolo system, a specially wired five-way pickup selector switch, and an output jack angled on the side of the body (so that when you step on the cable, it doesn't pull out of your guitar). I knew of course that these features would eventually be taken and used in other guitars, so I did something completely preposterous: I said, 'Put a handle in it!' That way, during videos and photoshoots I could swing the guitar around." Vai had several custom prototypes of these guitars built (which were used on the Eat 'Em and Smile tour) by Joe "Jem" Despagni, a custom guitar luthier and friend of Vai's. Due to Vai's highly coveted position in Roth's band, many guitar companies were eager to propose endorsement opportunities. In response to these offers, Vai sent out the specifications of the JEM guitar, detailing that the company that returned the best guitar would be given the endorsement. Dissatisfied with the guitars returned and unwilling to compromise, Vai held out on a guitar endorsement until Ibanez approached him, sending him an instrument superior to that of the other companies and willing to follow his instructions. After the pre-production prototypes were perfected, the first production Ibanez JEM 777 guitars were unveiled at the NAMM Show in 1987. Since its original 1987 release, the JEM has become one of the longest-running and most successful signature series guitars in history, with its sister guitar, the Ibanez RG, being the second highest-selling guitar (behind the Fender Stratocaster) on the market. Another design by Vai was the Ibanez Universe, the first production seven-string guitar, which was released in 1989. The Universe incorporated many of the aspects that made the JEM a unique instrument (24 frets, full floating tremolo, special pickup configuration, angled output jack, and deeper body cutaway), with an added low 'B' string, allowing for new low-range sonic possibilities. Used by Vai on much of Passion and Warfare and all of Whitesnake's Slip of the Tongue, the Universe was a large stepping stone for the burgeoning Nu-metal genre (with bands such as Korn having adopted the instrument and incorporating it into their signature sound). CANNOTANSWERAnswer this question using a quote from the following article:

What is JEM

Vai designed the Ibanez JEM guitar, a unique instrument that incorporated a series of groundbreaking designs