Here's a breakdown:

* Plants: Their cell walls are primarily composed of cellulose, which provides structural support and helps maintain cell shape.

* Fungi: Their cell walls are mainly composed of chitin, a strong and flexible polysaccharide.

* Bacteria: Their cell walls are made of peptidoglycan, a unique molecule that gives bacteria their shape and protects them from osmotic pressure.

* Some protists: Certain protists, like algae, have cell walls made of various materials, including cellulose, silica, or calcium carbonate.

Animal cells do not have cell walls.

The presence or absence of a cell wall is a key difference between plant and animal cells.