Corroboration is the evidence that is backed up by the initial evidence. For example, a witness says that I saw a man in black coat entering the store and buying a bag. Later, the saleswoman, who is another witness testifies that she sold the bag to the man in a black coat. In this case, both witnesses confirm the situation and the evidences coincide. When there is no corroboration, there is not any available source to confirm the same information.