A Sibelius 6 serial number is a series of numbers found at the back of the CD/DVD case for the software. The serial number is used to register the product at the Sibelius official website. For Sibelius 6, the serial number will begin with the letter "X."
The Sibelius software is used to create score sheets for their music pieces and is most often used by music industry professionals. Aside from making score sheets, the program also allows music playback using synthesized sound. The first version of the Sibelius was released in April 1993 after a seven-year development cycle. As of Oct. 6, 2014, the most stable up-to-date version of Sibelius is version 7.5.1.