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: 
**In the RAW+JPEG workflow, JPEG is what you shoot for. RAW is the safety net.**

The primary benefit or JPEG is not smaller files (that's the second), it is that **JPEGs are actually images**. Images have advantages over RAW files, already mentioned by others: quick preview, ready to email, no processing required, etc. Once the shot is taken you are done if you did things right.
Usually people do store in both formats to save their time (as they think), in case if JPEG is ok.

But I prefer to store only in RAW. All pictures without any problems (WB, expo, contrast, etc..) I convert in batch processing, in one-two clicks. The benefits are:

* I don't need to spend some time on filtering "JPEG or RAW"
* I always keep a chance to change something
* I don't spend much time to process well-shooted pictures (thankfully to batch processing)
* I save more space on my card in camera