Functional Endoscopic Sinus Surgery (FESS) is a minimally invasive procedure that effectively treats recurrent acute or chronic sinusitis and nasal polyposis by restoring sinus ventilation and normal function. The surgery involves using fiberoptic telescopes to open sinus air cells with minimal discomfort and a lower complication rate than conventional sinus surgeries. Patients can expect quick recovery and improvements in symptoms, with an estimated cost of $3500 to $4000, including accommodations and care in India.