Recently, the transaction-level modeling has been widely referred to in system-level design community. However, the transaction-level models(TLMs) are not well defined and the usage of TLMs in the existing design domains, namely modeling, validation, refinement, exploration, and synthesis, is not well coordinated. This paper introduces a TLM taxonomy and compares the benefits of TLMs’ use. Categories and Subject Descriptors C.0 [Computer Systems Organization]: General General Terms Design Keywords Transaction level model, modeling, validation, refinement, exploration, synthesis