This has to do with how audio, especially digital audio, is arranged and stored.

Often a source of confusion is the .cda file.  On a windows computer, when you insert a RedBook Audio CD, the tracks show up as .cda files.  One might assume that these are the audio files on the disc because they are the only items that show up in the explorer window. . . that would be wrong.  The .cda files are merely placeholders pointing to a place on the CD that the song starts.  Think of them as what windows calls a 'shortcut'.

In the past few months, we've had several requests for masters to be sent over the internet to the manufacturing plant.  DDP is the perfect format for this.  Many plants will give you FTP information to send the DDP master to their facility or a login to a webpage that you can upload the file.  I like this trend and recommend this for clients that have chosen replicators that accept DDP masters.

Blue Book is the name given to the Enhanced Music CD or CD-Plus (a dual session yellow/red books) format. Its name comes from the series of books, also called the 'Rainbow Books' that define all compact disc formats. The first session on the disc is a red book session and can be played on any CD player. The second session is a yellowbook session. This can be any data readable by a computer. There is almost no limit to what you can add to you audio CD release.

Yellow Book is the name given to the data compact disc (a common CD-ROM) format. Its name comes from the series of books, also called the 'Rainbow Books' that define all compact disc formats. It was developed by the creator of the compact disc, Sony/Phillips, and is now one of the most common CD formats.