When CD-R was first developed, manufacturers designed a file structure to suit their own requirements. This resulted in a complex set of CD-R standards for file storage, audio, video and photo storage. Writing software can establish separate 'Sessions' on a CD-R that enable data to be added later. Some can create music CDs from prerecorded WAV files, or even convert MP3 files directly to a CD that can be played back on your audio system.
More sophisticated software offers more features.
These range from specialist audio recording software that can clean vinyl tracks before creating a new audio CD, to design packages for CD covers and inserts. If anything goes wrong you can restore the CD-RW to its original condition and try again. To use this on your PC you'll need to install a driver that establishes the file format. The main advantage is that once a CD-RW has UDF it looks just like a removable hard drive on your system. You can then write files to the disc, delete them, create subdirectories and, provided another machine has a UDF driver installed, use the disc in it.