COB - Close Of Business
Close Of Business, also referred to as End of day or end of business relates to two different meanings which are closely related to each other.
The First definitions is related to the working hours of Stock exchange. "Close Of Business" is the time when the trading has stopped or in some situations a time where few minutes are left to the closing of session.
Second definition relates to normal working hours in any organization. Here, Close Of Business refers to the time of the day when the organization gets closed.
Suppose, we have a situation in which your boss tells you to return the documents before COB. This means you have to return them before the office closes its business today.