You know how phospholipids always look like they're facing outward? Well, it's because they have hydrophilic (water-loving) heads and hydrophobic (water-fearing) tails. The tails are on the inside of the phospholipid bilayer because they are hydrophobic. The heads, on the other hand, are hydrophilic, meaning that they face the outside of the phospholipid bilayer, towards the water.
The hydrophobic, or “water-fearing,” part of a phospholipid consists of its long, nonpolar fatty acid tails. The fatty acid tails can easily interact with other nonpolar molecules, but they interact poorly with water.
