It's actually neither. Basically, a necessary condition is something that has to happen for another event to occur; a sufficient one is something that is enough to produce an event. Thus, if we have a statement "if X, then Y," X is the sufficient condition for Y, and Y is the necessary condition for X.
To make this clearer, we can use a real life example. If it rains, I will get wet. It raining is sufficient for me to get wet. Me getting wet is a necessary condition for it raining (assume I'm not inside or don't have an umbrella). In other words, it can't rain without me getting wet.
Hope this helps! Sufficient and necessary conditions are definitely tricky.