  In online social network (OSN), understanding the factors bound to the role
and strength of interaction(tie) are essential to model a wide variety of
network-based applications. The recognition of these interactions can enhance
the accuracy of link prediction, improve in ranking of dominants, reliability
of recommendation and enhance targeted marketing as decision support system. In
recent years, research interest on tie strength measures in OSN and its
applications to diverse areas have increased, therefore it needs a
comprehensive review covering tie strength estimation systematically. The
objective of this paper is to provide an in-depth review, analyze and explore
the tie strength in online social networks. A methodical category for tie
strength estimation techniques are discussed and analyzed in a wide variety of
network types. Representative applications of tie strength estimation are also
addressed. Finally, a set of future challenges of the tie strength in online
social networks is discussed.
