Gann lines

hi, i am using forex.com software, and they give me a tool called ‘Gann lines’ i was wondering if anyone could shed some light on how to use this tool, and what it is for, i believe it is like fibonacci in that it shows s and r, so if that is the case, how do i apply it to my chart?

i use forex.com too… lol i didnt notice gann lines till this post. idk what they are for tho.