Clearly defines what is and is not considered Confidential Information between the parties to the contract and also makes clear how a party is able to claim confidentiality for information they provide to the other party.
It is common for large agencies and businesses to refuse to sign NDA’s, as a matter of policy, due to the amount of clients and data they handle. Signing an NDA can create additional liability for large organizations where one department may not know what the other is doing.
Smaller businesses and clients, especially those new to business are (sometimes rightfully) scared to share their “big idea” out of fear that the developer may steal it. In this instance, you have a ready made Mutual NDA that says they agree to be bound by the same terms and limitations they want to place on you.