Contracts and licenses
Contracts and licenses are not themselves intellectual property and are generally considered to be a distinct discipline, not part of the same area of law as intellectual property.
Nevertheless, contracts are essential to our system of intellectual property. They are the means by which you share intellectual property.
Contracts and licenses are the means by which people let their intellectual property out in a controlled way.

Importance

Normal people interact with contracts on a daily basis. There are contracts for cell phone service, contracts for parking your car, and contracts for starting a job. Each time you pay with a credit card, you are entering a contract.

Contracts are also everywhere in the business world. Contracts are used to buy office supplies, arrange loans, sell assets, and enter partnerships. In one way of thinking, the only way for a corporation to interact with the world is through the language of contracts.

That is because contracts are just agreements. People sometimes think of “contracts” as something official, whereas “agreements” are something less. This is not the case. Any binding arrangement is a contract under law and will be subject to the legal system.
When dealing with intellectual property, we make agreements about how that IP can be used.These agreements, called licenses in this context, are contracts. You see these licenses all the time when you enter the world of software. For consumer-oriented or open source software, these licenses are usually standardized as clickwrap licenses on websites or in installers, shrinkwrap licenses on software boxes, or open source licenses on Sourceforge. Commercial software is licensed too, but the much larger amounts of money involved usually lead to custom-negotiated multipage licenses with provisions specific to the parties (and the software) involved.