  In the white book of Bitcion, Satoshi Nakamoto described a bitcoin system
that can realize point-to-point online payment without a third-party
organization. After supporting this magical application scenario and subverting
the traditional centralized system, the blockchain technology has attracted
worldwide attention, triggered a research upsurge of blockchain consensus
algorithm, and produced a large number of innovative applications. Although
various consensus algorithms continue to evolve with the iteration of
blockchain products and applications, Proof of Work (POW) and Proof of Skake
(POS) algorithms are still the core of consensus algorithms. This paper
discusses two algorithms of POW and POS in blockchain consensus mechanism, and
analyzes the advantages and the existing problems of the two consensus
mechanisms. Since consensus mechanism is the main focus of blockchain
technology and has many influencing factors, this paper discusses the current
problems and some improved ideas, and selects some typical algorithms for a
more systematic introduction. In addition, some important issues related to
safety and performance are also discussed. This paper provides the researchers
a great reference on blockchain consensus mechanism.
