If you are getting serious about photography, you will eventually move away from JPG. You'll encounter two giants: RAW and TIFF.
RAW: The Digital Negative
A RAW file is the raw data dump from the camera sensor. It is not actually an image yet—it's just voltage readings. You must "process" or "develop" it using software like Lightroom.
Pros: Maximum editing flexibility. You can recover blown-out highlights or fix white balance after the fact.
Cons: Cannot be shared. You can't upload a RAW file to Instagram.
TIFF: The High-Quality Print Master
TIFF (Tagged Image File Format) is a processed image, but it is uncompressed (or losslessly compressed). It is the industry standard for printing.
Pros: Universal. Unlike RAW (which varies by camera brand), a TIFF opens on any computer. It holds incredible detail.
Cons: Massive file sizes. A single TIFF can be 100MB+.
The Workflow
Shoot in RAW. Edit in Lightroom. Export as TIFF for printing or archiving. Export as JPG for the web.