There are 3 kinds of discs, either CD or DVD:
- Commercially pressed discs, which have the pits and lands physically pressed into them (pits and lands are the physical equivalent of magnetic 0's and 1's)
- R discs, which have the pits and lands set by a laser "cooking" a dye - there are not quite as stable as commercially pressed discs, but close
- RW discs, which have the pits and lands set by the laser melting and re-crystalizing an aluminum alloy - which promptly starts to de-crystalize, taking all the data with it. At some point in time, the alloy was changed to make the discs less costly, and less reliable. You can't say in advance how long a given disc will last - usually months but it can be days or weeks or years, it varies from disc to disc - but it won't give you an engraved notice two weeks before it goes, it just goes when it goes.
RW media is useful for testing, or for transferring things between computers when there are no other options, and the original files are safely on the originating computer. Then it can be erased and re-used. (If you "delete" a file on either R or RW media, you do NOT gt the space back - you merely delete it from the TOC [Table of Contents]. The difference is you can erase the ENTIRE RW disc and start over.
If you want to make changes in something, you need to either follow Walt's advice, or use a Flash drive (aka Thumb / Keychain / Jump / Pen drive - they come in sizes up to 8GB) or an External Hard Drive in the first place.
Lynn
PS - I'd suggest you might want to remove your email address - these are public Forums, searched by google and other search engines, which in turn are searched by spammers seeking to "harvest" email addresses for spamming purposes ... altho it may already be too late.