NDA stands for non-disclosure agreement — a legally binding contract in which one or more parties promise to keep specified information confidential and not share it with anyone outside the agreement. Also called a confidentiality agreement, an NDA is one of the most common documents in business, employment, and deal-making, and signing one creates a real legal obligation, not just a polite promise.
What does NDA mean?
An NDA sets out four key things: what information counts as confidential, who is bound to protect it, how it may and may not be used, and how long the obligation lasts. Once signed, it creates a legal duty of secrecy, so disclosing the protected information to unauthorized people, even by accident, generally counts as a breach of contract. NDAs come in two main forms. A unilateral NDA binds only one party, typically the person receiving the information, and is common when a company shares secrets with an employee or contractor. A mutual (or bilateral) NDA binds both parties and suits situations where two companies exchange sensitive information while exploring a deal.
A well-drafted NDA usually also carves out exceptions. Information that is already public, that the receiving party already knew, or that must be disclosed by a court or regulator is typically excluded from the confidentiality duty. These carve-outs keep the agreement fair and enforceable rather than impossibly broad.
Where does NDA come from?
The abbreviation simply compresses the phrase “non-disclosure agreement.” The underlying legal idea — protecting confidential information and trade secrets through contract — developed as commerce grew more competitive and information itself became a valuable asset. NDAs became especially widespread in technology, entertainment, pharmaceuticals, and corporate deal-making, where a single leaked design, script, formula, or business plan can cause serious commercial harm. In research and healthcare, the same instrument often goes by “confidential disclosure agreement” (CDA), and universities and hospitals use them routinely when evaluating partnerships.
How is NDA used?
People sign NDAs in many everyday situations: starting a job, joining as a contractor, pitching to investors, discussing a possible merger or partnership, or receiving early access to an unreleased product. Businesses use them to shield trade secrets, customer lists, marketing strategies, financial figures, source code, and unpublished inventions. The word “NDA” is also used loosely in conversation to mean any promise to keep quiet, as in “we signed an NDA, so I can’t talk about it,” and it appears often in coverage of celebrities, startups, and legal settlements. In its strict sense, though, it refers to the formal written contract and its specific terms.
How long does an NDA last?
The duration of an NDA is set by the agreement itself and varies widely. Some cover confidentiality for a fixed term, such as two, three, or five years after the relationship ends, while others keep certain information secret indefinitely, which is common for genuine trade secrets that never become public. A well-written NDA also spells out what happens to confidential materials when the agreement ends, often requiring the receiving party to return or destroy documents and copies. Because these details determine exactly how long your obligations run and what you must do afterward, they are among the most important clauses to read before signing. If a clause seems unusually broad or open-ended, that is a good prompt to ask questions or seek advice.
Example sentences
- “Before the interview, the candidate had to sign an NDA covering the project details.”
- “The two startups signed a mutual NDA before sharing their technology.”
- “He violated the NDA by posting screenshots of the unreleased game.”
- “Our NDA lasts for five years after the contract ends.”
- “Investors reviewed the plan only after an NDA was in place.”
- “I’d love to tell you, but I’m under an NDA.”
Related and confusable terms
Related terms include confidentiality agreement and confidential disclosure agreement (CDA), which are essentially synonyms; non-compete agreement, which restricts working for competitors rather than sharing information; and non-solicitation agreement, which limits poaching clients or staff. A trade secret is the kind of information an NDA often protects, and a “confidentiality clause” is a similar provision built into a larger contract rather than standing alone. People sometimes confuse an NDA with a non-compete, but the two govern very different things: secrecy of information versus future employment and competition.
A note on legality
This article provides general information, not legal advice. NDAs are real contracts whose enforceability depends on how they are written and on the laws where they apply. Some jurisdictions limit clauses that would silence reports of illegal conduct, harassment, or safety concerns, and courts may refuse to enforce terms that are overly broad or against public policy. If you are asked to sign an NDA or need one drafted, consider having a qualified attorney review it so you understand exactly what you are agreeing to, what is excluded, and for how long the duty of confidentiality continues.
Frequently Asked Questions
What does NDA stand for?
NDA stands for non-disclosure agreement, a legally binding contract in which parties agree to keep certain information confidential and not disclose it to unauthorized people.
What is the difference between a unilateral and mutual NDA?
In a unilateral NDA, only one party is bound to keep information secret. In a mutual (or bilateral) NDA, both parties exchange confidential information and both agree to protect it.
What happens if you break an NDA?
Breaking an NDA is a breach of contract. The wronged party can typically sue for damages or seek a court order to stop further disclosure. Consequences depend on the contract and applicable law.
What information does an NDA cover?
NDAs commonly protect trade secrets, business plans, financial data, customer lists, product designs, and other sensitive material. The agreement itself defines exactly what counts as confidential.
Who signs NDAs?
Employees, contractors, business partners, investors, and companies exploring deals often sign NDAs. They are common whenever parties must share sensitive information to evaluate a relationship or project.
Is an NDA the same as a confidentiality agreement?
Yes, the terms are usually interchangeable. You may also see it called a confidential disclosure agreement (CDA), especially in research and healthcare settings.