1. Chitinous Cell Walls: Fungi have rigid cell walls made of chitin, a tough polysaccharide also found in the exoskeletons of insects. This provides structural support and protection.

2. Eukaryotic Cells: Fungi are eukaryotes, meaning their cells have a true nucleus enclosed within a membrane. They also possess other membrane-bound organelles like mitochondria, Golgi apparatus, and endoplasmic reticulum.

3. Heterotrophic Nutrition: Fungi are heterotrophs, meaning they cannot produce their own food. They obtain nutrients by absorbing organic matter from their surroundings. This can be done through saprotrophic (decomposers) or parasitic lifestyles.