A license is permission. A license is an authorization to use someone’s intellectual property or trade secrets on contractually specified terms. It is permission with conditions. Technically a license is an estoppel it precludes the owner of the IP from suing the user as along as the user is in contractual compliance.
It is worth repeating that an intellectual property (IP) license concerns an intangible (e.g. patent) that is infinitely divisible and inexhaustible. Therein lies the value of IP.
At its most basic, a licensor seeks to economically exploit its property, while a licensee seeks to use that property to generate income for itself.