Cell Membrane Overview
On the left you will see a mini cell. The blue thing around it is the cell membrane also know as the cell wall. This is a organelle that will keep everything not need out and everything needed in. This is a kind of wall surrounding what is inside. The cell membrane will usually around the cell so that it can protect the inside. Because how can it protect the inside if it is in the inside. That is the cell membrane.
More About Cell Membrane
The Cell Membrane also known as the cell wall is a not necessarily a organelle but it does surround the cell around it. It is like a blanket to keep the cell warm and safe. The cell membrane keeps it from getting anything not needed or not wanted. If there wasn't a cell membrane then anything could easily come in and out of the cell membrane. That would be dangerous for the cell and its organelles inside. That is why the cell membrane is a very important part in the cell.
Analogy of Cell Membrane
In the Middle Ages the cell membrane is like the wall of the city. It helps keep all that is wanted in all those attackers.