The cell wall is the protective, semi-permeable outer layer of a plant cell. A major function of the cell wall is to give the cell strength and structure, and to filter molecules that pass in and out of the cell.
A cell is the smallest part of an organism that still contains that organism's elements. The word itself comes from the Latin cella, meaning "small room." Although the word is found prior to the 12th Century, its application to a cell didn't come about until 1845, and the idea of a plant’s cell wall came about in 1848. Animal cells do not have such a cell wall, but instead have a membrane that serves as a boundary for the cell.
