Philes commonly refer to files about hacking in the days of BBSs. The use of ph in lieu of f is an homage to the word phone.
Other common abstractions of the word are t-files (shorthand for text files) and g-files (general files (etymology not certain)).
Their contents could vary from actual hacking and phone phreaking, sexual content, humour, technical information, down to subversive or so-called anarchy material about controversial topics such as poison brewing, homemade explosives, suggestions for making harmful pranks, urban terrorism "tactics", building homemade weapons and other similar information of dubious reliability, e.g. instructions for making a nuclear reactor out of a plastic barrel to keep in one's garden.
This term has been used throughout the entire run of the electronic hacker/phreak magazine Phrack as the name given to the articles/segments of the publication.
It is also used to refer to fans of the TV series The X-Files.