In this paper, we introduce closure operators [${cdot}$]c and [${cdot}$]a on a space and study some relations among [${cdot}$]c, [${cdot}$]a and countable tightness. We introduce the concepts of a strongly sequentially closed set and a strongly sequentially open set and show that a space X has countable tightness if and only if every strongly sequentially closed set is closed if and only if every strongly sequentially open set is open. Finally we find a generalization of the weak Fr$'{e}$chet-Urysohn property which is equivalent to countable tightness.