ELI5: Explain Like I'm 5

Lipid bilayer

A lipid bilayer is like a wall made of special molecules. Lipids are like small pieces of fat and they form a sort of barrier. The molecules link together to make a double layer, like two walls that are stuck together. This kind of wall is found in cells all around your body. It helps keep things inside the cell and also helps control what goes in and out of the cell.
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