Brief Answer:
different possible causes

Detailed Answer:
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There are different possible causes for swelling of the feet and ankles. The most common causes are: (1) venous disease- problems with the veins in the lower limbs can cause swelling

In most persons, if this is present, varicose veins are seen especially after a long period of prolonged standing or walking.
If this is the case, use of compression stockings, elevation of the feet on a regular basis during the day, may help

If there is no improvement, there are surgical doctor.

(2)heart disease- particularly heart failure, this is known to cause swelling.

There would normally be a history of hypertension or previous heart attack or history of other heart disease. Shortness of breath may also be present
An ECG and echo would be the baseline investigations needed to assess the function of the heart

(3)liver or kidney disease- both of these can cause swelling. Blood tests for the liver or/and kidney can determine if there is a problem

(4)trauma- trauma can cause swelling

(5)Arthritis of the ankle or small bones of the feet

(6)side effect of medication such as amlodipine that is commonly used for high blood pressure

If the swelling persists , then you should be evaluated by your doctor, this would include a physical examination and history of all relevant symptoms.

Treatment would depend on the cause found

I hope this helps, feel free to ask any other questions

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