While they are single-celled organisms, they share many characteristics with other fungi, including:

* Heterotrophic: They obtain nutrients from other organisms.

* Cell walls: Their cell walls are made of chitin, a complex carbohydrate also found in the cell walls of other fungi.

* Reproduction: They reproduce asexually through budding or fission, and sexually through the formation of spores.

It's important to note that the classification of living organisms is constantly evolving. While traditionally classified as fungi, some scientists argue that yeasts should be placed in their own separate kingdom. However, for now, they are still considered part of the Fungi kingdom.