Why are my feet swelling?

Many reasons: Feet may swell for a variety of reasons. Standing all day or sitting with your feet hanging down for a while. Circulation issues, the list keeps going. You should follow up with a doctor for a work up.

Gravity: Gravity pulls "excessive" fluid to the lowest part of your body. Excess fluid is either due to increased permeability of your vessels, increased fluid volume or inability to pump it.

Many possibilities: Some causes of swelling of the feet can include systemic problems such as hypertension, and problems with the kidneys and localized issues such as arthritis, infection, lymphatic obstruction, blood clots, varicose veins, trauma (fracture, sprain, and tendonitis) and side effects to medication. Have it evaluated by a professional and get the appropriate treatment.