In this review, various synthetic and structural aspects of methylaluminoxane and the elementary processes involved in olefin polymerization, as identified by various spectroscopic techniques, are detailed. Various boron-based counterions and their interactions with metallocenium cations are discussed. A comparison between MAO and boron-based activators in terms of catalytic activity and polymer characteristics is made. Finally, the use of the above system in the polymerization of cationically polymerizable monomers and acrylates is discussed.