Plant cell walls are rigid structures that surround the cells of plants, providing support and protection. Made primarily of a substance called cellulose, these walls help maintain the shape of the cell and prevent it from bursting when water enters. The cell wall also acts as a barrier, controlling what substances can enter and exit the cell. In addition to cellulose, plant cell walls contain other materials like hemicellulose and pectin, which contribute to their strength and flexibility. This unique structure allows plants to grow tall and withstand various environmental pressures, making them essential for the overall health and stability of the plant.