Disability insurance secures an individual’s income at least partially if he or she is disabled because of an illness or injury and unable to continue doing their occupation. Policies vary in what the definition of a disability is. Some policies pay claim if the insured is unable to do the job they are qualified to do, for example a surgeon. His pay is up quite high and his skills are tuned to that one job. If something happens to him and he is unable to continue work as a surgeon, then anything else he does will not give him the income he may have planned for or need. Thus disability insurance protects that lost income.