This is an ever expanding list of ways that slips can be worn!
Slips are great to improve the hang or line of a dress. They can prevent dresses or other garments from clinging to tights or undergarments.
Slips can protect more delicate garments from rub or exposure against your skin and also from perspiration.
Slips can be used if you are wearing sheer dress.
Slips can add an additional aspect to an outfield. People will often have part of their slips be visible such as the hem.
Slips don't have to be just practical, they are commonly worn as negligee.
Slips can be worn as sleep wear.