1. a detailed investigation into someone/something in preparation for a business transaction
do due diligence on someone/something
'Due diligence' refers to the actions a person or company takes to ensure a reasonable amount of care or safety for themselves or others. Examples of due diligence at home, for example, might be taking security precautions such as locking your door and closing windows to ensure someone can't break-in easily to your home. In business affairs due diligence can also refer to the process of examining financial information of a company or organisation before making an agreement to work together or do business together. You will usually only hear this term used to discuss legal or business matters.