With the progress in refractory castable technology also bonding systems have been developed and evolved. The binder technology evolution is in many cases the key driving force behind innovations in the field of refractory castables, both with respect to ultimate performance in application but also installation technology evolution. Today a large range of bond systems is available either as proprietary systems or commercial products. This paper will provide a state of the art review of the different bond systems for refractory castables by their function and their delivered performance. Bond systems will be explored via an extensive literature review along with a perspective of their evolution over the last two decades. A specific focus will be given to bond systems for alumina-based monolithic castables as they play an increasingly important role in the global steel industry and which is by far the biggest consumer of refractory materials. The different comparative characteristics for each bond system and their advantages as well as the tradeoffs and constraints will be discussed. This then gives rise to the notion that there is no one universal bond system but rather intrinsic characteristics have to be adapted to each situation. Conclusions will explore future needs and development options.