What does it mean that a DVD has one layer or two?

Question

What is the difference between these two types of dvd? If I erase one layer, I must erase the second two? Why are these layers symbolised by + and -?

Answer 1

http://electronics.howstuffworks.com/dvd3.htm

Answer 2

Double layer means that the DVD can hold 2x more data. The second layer is on the SAME SIDE just deaper, the lazer beam focuses at a different depth to read the second layer. Almost all DVD movies have 2 layers, thats why the movie pauses or jumps for a second in the middle of the film as it switches form the first layer to the second

Answer 3

Double layer DVD is a dvd that you can write information on both sides. so you can put the movie on one side and the extras on the other side. as far as the - +. those are just formats. either will do the same, some dvd players only play a certain type so you might want to check that out.

Answer 4

+ and - just refer to how the disc is writable. DVD+R or RW is the most compatible type

dual layer is like two DVDs in one (twice the info stored)

Answer 5

Layers aren't sybolized by + and -...two layer just means two layers of burning surfaces so you can store double the amount of information. + and - define the burning standard used.