Online banking systems have become ubiquitous enough that today, some banks have done away with their brick-and-mortar stores and only offer online resources. The rise of computerized banking makes it useful to have an overview of the system on hand. A banking system has a variety of classes, which can be quickly outlined with a class diagram. The diagram below shows how items in the system interact, providing a helpful look at tellers, customers, account types, and other factors involved in banking.