Many people use “further” and “farther” interchangeable, but, in fact, they mean slightly different things. “Farther” refers to a physical distance, while “further” refers to a figurative distance. In most cases you will use 'further', but for the MOST part 'further' is more figurative, and 'farther' is more literal. Example: I was further along in my education, then I would have imagined. The nearest house was much farther than she thought.