A critical illness refers to a severe health condition that poses a significant risk to a person's life or long-term health. Examples of critical illnesses include heart attack, stroke, and cancer. These conditions often require immediate medical attention and can lead to serious complications if not treated promptly. Many people choose to purchase critical illness insurance to help cover the costs associated with treatment and recovery. This type of insurance provides a lump-sum payment if the policyholder is diagnosed with a covered illness, helping to alleviate financial stress during a challenging time.