Co-ownership is a way of organizing the ownership of a property.
In co-ownership, there are at least two owners. There can be many more.
The building or complex is divided into :

• - private parts, which belong to a co-owner,
• - common parts, which belong to all the co-owners, gathered within the syndicate of the co-owners.

The co-ownership can concern as well :

• - a building, in which case we speak of " vertical co-ownership ": each co-owner owns an apartment, a cellar, a garage, etc. The structure belongs to the co-ownership.
• - a group of houses, this is called " horizontal co-ownership ": each co-owner owns, generally, his or her house, built on land that belongs to the co-ownership.

Each co-owner is the owner of a lot, which consists of :

• - a private part,
• - a share of the common areas.

All the co-owners form the syndicate of co-owners, which is responsible for administering the common portions and maintaining the building.
In order to act, the syndicate of co-owners is represented by a syndic. The syndicate of co-owners takes its decisions in the assembly of co-owners. The syndic then takes care of the execution of the decisions.

Note: there are other ways to organize a building or a real estate complex: civil company, syndicate association... These other forms obey different rules than the co-ownership.