According to Wikipedia, Due Diligence is:
"Due diligence" is a term used for a number of concepts involving either an investigation of a business or person prior to signing a contract, or an act with a certain standard of care. It can be a legal obligation, but the term will more commonly apply to voluntary investigations.
I have seen the use of this word from a lot of individuals lately. In particular, the people once connected with Trace Trajano. For some reason, Bo Sanchez, Jomar Hilario, Larry Gamboa et al., have moved on separate business paths.
