Pension
Pensions are a common retirement plan that many companies offer. These plans have become less polar in recent years with the advent of other retirement accounts like 401(k)s and IRAs. With most pension plans, companies bear the brunt of the risk of benefits due to retirees, so pension plans can be expensive for companies to maintain and fund sufficiently.
Public pensions for goverment workers, both at the federal and state levels are still very common, while pensions plans in the private sector have diminished. Historically these plans were the most popluar, and sometime only option available, even up through the 1980s. As the population gets older and lives longer, defined benefit plans can be difficult to maintain. This means that for each worker in the system, there are becoming more and more retired people recieving benefits. This same issue also impacts other programs like Social Security.