The CD-R was made to be compatible with all devices that utilize the same medium, even though the method of writing data into the disc differs slightly compared to traditional CDs. The CD-R was also known as ‘Write Once Read Many’ because of the fact that you can only write to the disc once. This might be a little bit confusing since you can actually write on a CD-R a few times since it allows writing to the disc in increments. The CD-R medium also brought forth its own drive. The CD Writer is a drive that looks and acts like a normal CD-ROM but with the capability to write data into CD-Rs.
What you do on a CD-R is to erase the old data and replace it with a new one. Once the disc is full, you cannot add or replace data on it. That shortcoming has been remedied by the appearance of CD-RW discs. These discs are very similar to the CD-R but have the added feature of being erasable. Erasing the data in a CD-RW disc makes it revert to its old state and can be used just like a blank disc. The technology of CD-RW requires much better optic technologies than what CD-R requires, thus CD Writers cannot write into the CD-RW. Although backwards compatibility means that all CD writers and some of the older CD-ROMs could read a written CD-RW.
CD-Rs do have a few advantages over the CD-RW, one of which is the fact that that the former costs a lot less compared to the latter. CD-Rs are also a lot more reliable in storing data due to the unstable nature of the alloy used in CD-RWs. Read and write times are also significantly higher in CD-RWs causing longer wait for the user. With those arguments, the CD-R and CD-RW are just about even when weighed in. CD-Rs are appropriate for storing data for long periods of time like in back-ups while CD-RWs are excellent when transferring files from one PC to another due to it reusability.