A custodian is a person or a corporation that legally has custody of something or someone, from artifacts in a museum to the records of a hospital or law firm to financial information and instruments. People who are held in custody are almost always prisoners, whether military or civilian. Typically, an individual legally responsible for another human being who is not their own minor child is called a guardian, not a custodian.
Custodians also serve as janitors. They often clean and provide basic maintenance for a building and sometimes its contents. In museums and historic buildings, custodians can be highly skilled, responsible and valuable employees. Custodians are also often responsible for the physical security of a building, particularly opening it for business and securing it at night.
A depository is a place where things are deposited for safe-keeping. Libraries are one of the most important types of depositories. The role of the library in safeguarding and maintaining information is so important that the United States government has distributed a wide variety of materials, from bound print journals to microfiche, to some 1,250 libraries across the United States. There are also genetic depositories such as Norway's Svalbard Seed Bank.
Financial depositories are typically banks or credit unions. Rather than hide their money at home, where it is vulnerable to loss, fire, theft and spending, clients deposit their money in a bank or credit union. Financial instruments, valuable jewelry and important papers are usually stored in individual safe deposit boxes but money is pooled, each depositor being credited for the money deposited. In the United States, depositors are insured up to $250,000 "per depositor, per insured bank, for each ownership category," according to the Federal Deposit Insurance Corporation (FDIC).