The process of copying files to a CD is called

Writing data onto an optical disc such as a CD or DVD, using a laser in an optical drive to record it onto the disc's recording layer, is called burning. It is the standard term for the write direction (computer to disc), distinct from other disc-related operations such as reading data back off a disc.

The question describes copying files TO a CD, i.e. writing data from a computer onto the disc. This is exactly the write-direction operation defined above, so it matches Burning.

• Zipping refers to compressing one or more files into a single compressed archive to reduce storage size or ease transfer; it is a compression operation, not a disc-writing operation.

• Digitizing refers to converting analog information, such as a printed image, a sound, or a physical document, into digital form that a computer can process; it is a conversion operation, not a disc-writing operation.

• Ripping refers to extracting or copying content FROM an optical disc onto a computer's storage, i.e. the read direction; it is the reverse of writing data onto a disc.

So the correct term for copying files to a CD is Burning.