A shift dress is a dress in which the cloth falls straight from the shoulders and has darts around the bust. It frequently features a high scoop or boat neck. Shift dresses are often confused with the sheath dress, which is form-fitting and shaped by tucks on the waist area. Shift dresses became popular in western fashion in the 1920s and were revived in the 1960s. They are most flattering on body types that are more like columns. - Wikipedia
Nancy Queen (i believe her real name) at her site "Shopping on Champaign" made these comments about How to Wear a Shift Dress:
How to Wear a Shift Dress
WHEN SHOULD YOU WEAR A SHIFT DRESS?You can wear shift dresses for so many events - both special events and everyday occasions.
Worn with a pair of heels and dressier accessories, a shift is suitable for wedding guest attire, cocktail parties, formal events, church or synagogue, date night, bridal showers, and business dinners.
Alternatively, you can wear shifts for casual events as well. Just adding more casual shoes such as sandals, mules, slides, or even sneakers, will give your dress a more relaxed look. I like to layer my shifts with a denim jacket or sweater over my shoulders for a casual yet pulled-together look.
Her Pro Tip:
Keep a few shift dresses in your closet for when a special occasion pops up. Then you won’t have to rush out and buy an entirely new outfit, you’ll have everything you need right in your wardrobe.