You aren't gonna need it
Software engineering principle / From Wikipedia, the free encyclopedia
"You aren't gonna need it" (YAGNI) is a principle which arose from extreme programming (XP) that states a programmer should not add functionality until deemed necessary. Other forms of the phrase include "You aren't going to need it" (YAGTNI)  and "You ain't gonna need it" (YAGNI).
Software engineering principle
Ron Jeffries, a co-founder of XP, explained the philosophy: "Always implement things when you actually need them, never when you just foresee that you [will] need them." John Carmack wrote "It is hard for less experienced developers to appreciate how rarely architecting for future requirements / applications turns out net-positive."