Protoplasm is an old term, which means the living substance that makes up a cell. It is no longer much used. Biologists prefer to talk about the cytoplasm and the cell nucleus.
In plant cells, it is surrounded by a cell wall. In animal cells, the whole cell is made of protoplasm, surrounded by a cell membrane. Protoplasm in living beings is made up of about 75–80% water. However, this is rather misleading because the cytoplasm is full of structures called organelles, which do various tasks. The endoplasmic reticulum is the largest of these structures; there are many other organelles.