Creations of the mind — designs, code, writing, logos, ideas — that can be owned and protected by law, then sold or licensed by contract.
Intellectual property is the stuff you make that has value but isn’t physical: a logo, a chunk of code, a marketing plan, a photograph. Because it can be owned, it can also be transferred, licensed, or fought over — which is why every service contract needs to say who ends up owning what.
For sellers, the default under copyright law is that you own what you create until a contract says otherwise. That’s leverage. You can sell full ownership, or you can license specific uses and keep the rest — often a better deal than handing everything over for one flat fee.
For buyers, don’t assume paying for work means you own it. Ownership transfers only when the contract clearly says so, usually through a work-for-hire or IP-assignment clause. Pay for a logo without one and you may only have permission to use it, not own it.
The whole category splits into pieces worth knowing separately: copyright protects creative works, trademark protects brand identifiers, and licensing grants use without transferring ownership. Spell out which one your contract is actually dealing with.