You can change this option so you can copy files to the CD using the Windows Live File System, eject it, and later copy other files to the same CD from the same computer.

Once you are done with the day’s transferring, connect the flash drive to your computer and copy the files there so you have an archive. It will only take a minute or so. That way if something ...

I burned some files onto a CD-RW using Toast, but now that I'm trying to copy them back into my hard drive (running 10.3.3) it won't let me. More specifically, just when it's about to be finished ...

Multi-session CDs or DVDs allow you to use the disc several times. You burn some files, take a break, then burn more files on the disc’s remaining space. You can burn several sessions onto the disc.

An alternative is to put the software CD into your old computer, copy the application to a temporary directory, copy that to a flash drive, then install it on your new computer.

Secure Copy is a UNIX standard used to transfer files from one computer to another. He's how to use the function in macOS, all via the Terminal window.