What is an "AAC Version"?

1. Because that’s what the current iTunes encoder is.

2. Click here for information.

(120018)

owen.nik wrote:

When I right click on a song, why is there an option to make it an "AAC Version"?

iTunes has the ability to convert songs to different audio encoding format.

Unless you have some special need for a different format, you can safely ignore that option.