Employment and Support Allowance (ESA) is a benefit paid to people who have a disability or health-condition that affects how much they can work.
Incapacity Benefit and Severe Disablement Allowance were two benefit that have now been discontinued to new claimants and have been replaced with ESA, but there are a small number of people who are still receiving either Incapacity Benefit or Severe Disablement Allowance (who have been claiming that benefit for quite a long time).