Though bitter, it is a fact that one out of each five men and one out of each six women in UK experience some kind of critical illness before their normal retirement age. In fact, nobody ever cherishes the nightmare of suffering from critical illness. But still they happen to face such illnesses in their life. And the consequences of experiencing such fatal diseases are simply devastating!With sophisticated treatment available in the UK, it is not at all difficult to recover from critical illnesses. But the expenditure of such treatment is high enough to make somebody broke. Hence, the trend of taking out critical illness insurance is prevailing in the country. In order to ensure a financially secured future, insurance works as a godsend.However, the matter of critical illness insurance is a bit dicey. The definition of critical illness varies from agency to agency. One illness that is critical to one company may not be so to the other. You find it funny, yet it is true that a brain tumor might be seen as a brain tumor if it is a pituitary adenoma rather than a meningioma. Hence, while one purchases a policy, it is recommendable to know how it describes certain illnesses and what exactly it covers.It will take a vast space to give an exhaustive list of all the critical illnesses. However, the ones that are universally accepted as critical are Mocardial infarction (heart attack), invasive maligancies (cancer), stroke with neuralgic, residuals, Alzheimer disease, kidney failure, multiple sclerosis, organ transplant, paralysis of limb, blindness, deafness, and total disability.Health care nowadays are highly expensive; and if it is a critical illness then the expenditure will have no limit. So, it makes real sense to go for an insurance to keep you protected against any kind of mishap. It is never a happy idea to think about illnesses; but it is wise to be prepared against the worst.