DVD+R and DVD-R are two incompatible formats that define differing writing procedures for slightly different media types. It is important to realize that if you purchase a DVD-R writer you will not be able to write to DVD+R media. Conversely, if you purchase a DVD+R writer you will not be able to write to DVD-R media. Most modern-day DVD writers are dual-format capable (ie- a DVD+/-RW drive) and they can write to both DVD+R and DVD-R media. If possible, it is better to purchase a Dual-Format capable drive to ensure that you will be able to write to both media types.