  Blockchain has attracted significant attention in recent years due to its
potential to revolutionize various industries by providing trustlessness. To
comprehensively examine blockchain systems, this article presents both a
macro-level overview on the most popular blockchain systems, and a micro-level
analysis on a general blockchain framework and its crucial components. The
macro-level exploration provides a big picture on the endeavors made by
blockchain professionals over the years to enhance the blockchain performance
while the micro-level investigation details the blockchain building blocks for
deep technology comprehension. More specifically, this article introduces a
general modular blockchain analytic framework that decomposes a blockchain
system into interacting modules and then examines the major modules to cover
the essential blockchain components of network, consensus, and distributed
ledger at the micro-level. The framework as well as the modular analysis
jointly build a foundation for designing scalable, flexible, and
application-adaptive blockchains that can meet diverse requirements.
Additionally, this article explores popular technologies that can be integrated
with blockchain to expand functionality and highlights major challenges. Such a
study provides critical insights to overcome the obstacles in designing novel
blockchain systems and facilitates the further development of blockchain as a
digital infrastructure to service new applications.
