Question: DSLRs often have the ability to store both a JPEG and a raw file.

Given that the [primary benefit of in-camera JPEG over raw](https://photo.stackexchange.com/questions/15/what-are-the-pros-and-cons-when-shooting-in-raw-vs-jpeg/115#115) is the smaller filesize, and that JPEG+raw is going to store even more data than raw alone, it seems like you're just wasting space on your card and [making your workflow more complicated](https://photo.stackexchange.com/q/4453/378) if you store both.

Why bother storing both JPEG and raw in camera, instead of just a raw file?

Answer: 
My understanding is that the convention of RAW+JPEG started early in pro digital photography (like Sports Illustrated at a bowl game) when computers were slower than they are today and RAW file tools more cumbersome to use. The idea would be that Photo Editors would look through the JPEG files to find the shots they needed. They then sent the corresponding RAW files to the technicians who would convert and tone those images. It assumes a multi-person workflow.

That said, a lot of news organizations just used JPEG files -- especially when they had to transmit files on deadline over a land line modem.
I've suggested RAW+JPEG to photographers who are fairly new to digital photography and are ambivalent about switching to a raw workflow, because they don't have raw-capable tools or are worried about the effort involved. I point out that they can keep using the JPEGs like they always have, but the raw files will be there, like a digital negative, for whenever they're ready to work with them.