JPEG and Raw are two different types of digital files. When photographing with a digital camera you are able to save your images in Raw or JPEG format (sometimes both). A Raw file is an uncompressed version of an image containing more data. JPEG is the 'simple' version of a digital image. A controversial question amongst professional photographers which file format is better Raw or JPEG?
Raw files contain more data than JPEG images, and as a result if you underexpose, or overexpose an image, you are more likely to save the image if it is in RAW format. There will be more information in the overly dark shadows, and overly bright highlights that you will be able to draw from during the post processing. Another good thing about Raw files is that they do not deteriorate the way JPEG files do. When you edit a RAW images a profile is attached to the image called an xmp that contains the editing information. When you an open and close a Raw image to process it this is the file you are viewing. This is not the case with JPEG files. Every time you open and close a JPEG file you are losing small amounts of Data, and over time this will affect the quality of the image. If you open and close a JPEG too many times your images will begin to lose definition and begin to look pixelated.
With JPEG files you are able to attach an in camera profile that saturates color, increases contrast, or adds sharpness. While increasing the control in the camera, you are decreasing the amount of time you spend post processing. Adding the contrast in the camera eliminates an extra time consuming step during editing. Raw files are also larger than JPEG files because they are uncompressed and take up more space. Therefore you are able to take less photographs when shooting in Raw format.
In the end the choice is up to the portrait photographer. Both JPEGs and Raw files have their positive and negative attributes, you must decide what is most important for you and the type of photography you are doing. Do you need to be able to take mass quantities of photographs without worrying if you have enough space on your card during a photo shoot? Or are you a less confident photographer who would like the comfort of knowing that if you mess up you are more than likely able to fix an under or overexposed image?