Why do we use soap?

We use a soap to clean away the dirt, but what is dirt really? Dirt can be a combination of water soluble and fat soluble components that got stuck on our skin or on our garments. Water can clean away anything that is water soluble (polar-polar), but the fat soluble dirt can only be cleaned with the help of soap. Soap has hydrophobic (has affinity to fat) and hydrophilic (has affinity to water) sides which allows it to remove any fat soluble dirt when washed along with water.