Can CDs sent by companies as a promotion be re-used? How can you tell what kind they are?

Answer 1

CDs that can be reused are CD-RW (re-writable). They are much more expensive than CDs that can't be reused (CD-R). When companies send out promotional CDs, they won't waste money so they use the CD-R version. Sorry, but you won't be able to erase and re-record.

Answer 2

No they are most likely no reusable unless you consider a drink coaster as a reuse.