Rewriteable CDs- eraseable?

once you have written to a CD-RW, and you “append” to it (“erase,”) it’s not really removing data from the CD is it? In other words, each time you do that you lose MB from the CD, right?

I have’nt really used them, but i was under the impression that once it’s gone, it’s gone for good, completly erased.

Yes, a CD-RW is truly erasable. What’s gone is gone, you get the space back.