What are micelles?

Micelles are spherical structures formed by lipid molecules in an aqueous solution. Micelles form when a sufficient number of amphipathic molecules, such as phospholipids or fatty acids, are added to water. 

Micelles are made up of both - hydrophilic (water-attracting) as well as hydrophobic (water-repelling) regions. The hydrophilic, polar head groups of the molecules face outwards, forming the outer layer of the micelle and interacting with the surrounding water. In contrast, the hydrophobic tails are shielded within the structure, preventing them from interacting with water.