These days even some smaller cameras give you the option of picking a file format to save in, normally RaW and/or jpg.

The easiest way to describe the two of these is that RaW is like an old film camera negative, jpg is like the fully processed image.

RaW is bigger because it stores pretty much everything it sees, what you snap is what you get and it's far more adjustable when taken from the camera.

Because of the way the information is held things like white balance, exposure, saturation and sharpening can be done to the original file and is overlayed over the image so is infinitely removable and replaceable.

Jpg's on the other hand are processed and "flattened" so, although they can be edited, changing things is harder because the computer is having to work with something already saved, an already compressed image.

Jpgs are smaller because they've been put through a compression algorithm, the processor marks a pixel of a specific colour... then marks for how many pixels that colour appears.

That's why a photo, for example, of a postbox would be smaller when compressed than a bunch of flowers, the computer thinks, right, that pixel is red... and now for the next however many pixels I just repeat red... the only information saved is that first pixel and a short note saying "repeat for this long..."

To make a hopefully understandable analogy to editing RaW vs jpg, imagine you're baking a cake.

Editing RaW is like adding more brandy to the mixture before you put it in the cake tin and bake it.

Editing jpg is like baking the cake then adding the brandy by pouring it over the top, it's sort of the same... but the result won't be as good because it wont change the whole cake, merely the top layer of it.

Oh, an addendum... I have no clue about baking, this just sounded logical and may have no actual truth in cake preparation... but that's what the recipes group is for ;)

Really both formats have their uses, if you don't mind a little post-processing RaW is easily the best but if you'd rather just snap and get the image straight from the camera without having to play with it then jpgs are the way to go.

My thoughts? I'd never not shoot in RaW...