Basics

A DVD burner can read and create copies of DVDs, and it can place data onto a blank DVD. By default, a blank disc has about 4.7 gigabytes of space--enough for an encyclopedia and then some.

Dual Layers

A dual-layer DVD doubles the available space on a blank disc, but it requires a drive that can recognize a dual-layer DVD. However, a feature film DVD can contain as much data as a dual-layer DVD but not require a dual-layer DVD drive.

DVD Media

The standard blank DVD is a "DVD-R" or "DVD+R" and can only have data put on it once. You can add more data in multiple sessions, but you cannot remove or replace data on this type of disc.

RW

"RW" means "re-writable." In this case, you can delete and replace files as much as you like (although there is typically a theoretical limit of about 10,000 rewrites). The surface of this disc is different from a standard blank DVD, and may not be readable by a car or home stereo.

Features

Like DVDs, you will see both "DVD-RW" and "DVD+RW" discs. Modern DVD burners use the "DVD/RW" label to indicate that they are compatible with both types of rewritable DVDs. Due to its different surface, it takes much longer to burn this type of disc.

Source:

Recordable DVDs

DVD+RW FAQ