Here's a breakdown:

* Phospholipids are the primary building blocks of cell membranes. They have a unique structure with a hydrophilic (water-loving) head and two hydrophobic (water-fearing) tails.

* Bilayer means that these phospholipids arrange themselves in two layers. The hydrophilic heads face the watery environments inside and outside the cell, while the hydrophobic tails are tucked away in the middle, away from water.

This arrangement creates a flexible and selectively permeable barrier that controls what enters and exits the cell.

While the phospholipid bilayer is the most abundant component, other molecules like proteins, cholesterol, and carbohydrates also contribute to the structure and function of the plasma membrane.