Fleece jackets are one of the most comfortable and versatile pieces of outerwear out there. You can easily wear a fleece jacket with a longsleeve or button-up shirt underneath, but they can also be used as a layering base. If you're the outdoors type, the go-to look is with a down vest over top, but a fleece jacket can also be placed underneath a lightweight parka or shell for when it gets colder to give you the right amount of warmth.