  In the theoretical study of distributed communication networks, "history
trees" are a discrete structure that naturally models the concept that
anonymous agents become distinguishable upon receiving different sets of
messages from neighboring agents. By conveniently organizing temporal
information in a systematic manner, history trees have been instrumental in the
development of optimal deterministic algorithms for networks that are both
anonymous and dynamically evolving.
  This note provides an accessible introduction to history trees, drawing
comparisons with more traditional structures found in existing literature and
reviewing the latest advancements in the applications of history trees,
especially within dynamic networks. Furthermore, it expands the theoretical
framework of history trees in new directions, also highlighting several open
problems for further investigation.
