This chapter defines co-ownership and its two main types under civil law: co-ownership by shares (tenancy in common) and joint co-ownership (joint tenancy). It outlines their respective legal relationships and briefly introduces quasi-co-ownership. The text explains that civil law traditionally emphasizes sole ownership for individual autonomy and economic efficiency. It provides a comparative historical perspective, referencing Roman law’s co-ownership (similar to tenancy in common) and Germanic law’s joint ownership, noting that modern Chinese law adheres to the dichotomy of the two main types while incorporating elements from foreign legal systems. The analysis also acknowledges that some arrangements, like partnership property, can exhibit characteristics of both types.