A more thorough explanation:

A concordat is an agreement between a government and a church, usually the Roman Catholic Church. It can also refer to an agreement between ecclesiastical persons concerning a benefice, such as a resignation or promotion. The term is increasingly used only for treaties concluded with the Holy See.

• In 1929, the Lateran Treaty was signed between the Holy See and Italy, which established Vatican City as an independent state and recognized Catholicism as the official religion of Italy. This is an example of a concordat between a government and a church.
• In the Middle Ages, a concordat could refer to an agreement between ecclesiastical persons concerning a benefice, such as a bishopric or abbey. For example, a bishop might agree to resign from his position in exchange for a promotion to a higher position within the church.
• A concordat can also refer to an agreement between secular persons or entities. For instance, two companies might sign a concordat to work together on a joint project.

These examples illustrate the different types of agreements that can be considered concordats, from treaties between governments and churches to agreements between individuals or organizations.