no no no,

not a picture/image


an electronic image of the disc, imagine the whole dvd/cd disc has been read onto your hard disc and stored as a single file that is 4.7gb ot 700mb respectively, alcohol can read this single file (image) as treat it as a virtual disc,

if you dont download a lot of big stuff you may not get the point of it - but once you have lots and lots of files that are downloaded and are on .ISO or nero images etc it become VERY useful as you dont need to keep loading discs into your machine - if you have a huuge hard disc it makes sense to keep image files of them on there Rather than using the actual cd/dvd each time