How search engine programs and the algorithms actually work?
How search engines and algorithms work, for this where both IT and math experience is useful. People who have programmed at a detailed systems level have a natural feeling for how spiderbots will read a page, what they will search for, what tables they will set up, what weightings they may give to different elements. All of this builds a picture of the database that will be created and how it will be accessed when a search is undertaken. Unfortunately, this skill is the most difficult one to learn because it relies on many years experience of systems programming.