What is the internal control segregation of duties all about?

Answer 1

Segregation of duties is one of the specific internal controls to ensure no one employee has so much control over an activity that mistakes could go undetected or that the employee could be placed in a situation where they could be tempted by an inappropriate activity. The emphasis is the Segregation of functional responsibilities to create a system of checks and balances, so that a duty performed by one staff would be checked by another staff in the ordinary course of work. Read more on this at the 1st link and 2nd links.

The article What is Effective Internal Control? at the 3rd link should be very useful to you too.

Answer 2

Example: The person writing checks does not also reconcile the bank account. He could write a check to himself or a friend and no one would know. It's to prevent fraud ,theft, and errors. The theory is that you don't allow one person to have too much control.