What is very useful handy reference guide for questions alternative to Wikipedia and disappears just when you get used to the resource?

A very useful handy reference guide that fits this description is "Quora." It provides a platform for users to ask questions and receive answers from a community of knowledgeable individuals. However, it can sometimes feel inconsistent, as discussions and popular threads can disappear or become less accessible over time, making it challenging to rely on for long-term reference.