The owner (first party) of property can license that property. The receiver of the license is called the Licensee (second party). If the License permits, the Licensee can license some or all of its rights to a third party. That license is called a Sublicense and the third party is the Sublicensee.
Another way to think of it is comparing it to a building. The building may have a main floor, a basement, and a sub-basement. Those levels would be comparable to an owner, a Licensee, and a Sublicensee.
In contract jargon, the third party is often the party that is not executing the contract. So in the License, the sublicensee is not an executor of the contract and will be referenced as a third party. In the sublicense, the owner does not typically sign the agreement and is thus referenced as the third party. Therefore, the first/second/third party terms can be transitory and framed according to the agreement.
Answered on Oct 15th, 2013 at 2:44 PM