The difference between DVD-R, DVD+R, DVD+RW and DVD-RW

There’s DVD+R, DVD+RW, DVD-R, DVD-RW, and even DVD-ROM! So what’s the difference between all of these different names, aren’t all DVDs the same? Well, it’s not quite that simple. Let’s first start with the most obvious difference: some have R and some have RW. The “R” stands for readable, while the “W” stands for writeable. [...]