You wear compression stockings to improve blood flow in your legs.  Compression stockings gently squeeze your legs to move blood up your legs. This helps prevent leg swelling and, to a lesser extent, blood clots.

person putting on compression stockings

If you have varicose veins spider veins, or have just had surgery, your health care provider may prescribe compression stockings.

Wearing stockings helps with:

• Aching and heavy feeling in legs
• Swelling in legs
• Preventing blood clots, primarily after surgery or injury when you are less active

source:https://medlineplus.gov/ency/patientinstructions/000597.htm