In recent years, crypto-currencies (a form of decentralised digital currencies) have been quite popular as an alternative form of payments. They are underpinned by a breakthrough technology called Blockchain which extensively use a number of cryptographic mechanisms and other advanced techniques from the domain of distributed computing. This blockchain technology has received unparalleled attention from academia, industry, and governments worldwide and is considered to have the potential to disrupt several application domains, other than currencies, touching all spheres of our lives. The sky-rocket anticipation of its potential has caused a wide-scale exploration of its usage in different application domains. This has resulted in a plethora of blockchain systems for various purposes. However, many of these blockchain systems suffer from serious shortcomings related to their performance and security, which need to be addressed before any wide-scale adoption can be achieved. A crucial component of any blockchain system is its underlying consensus algorithm, which determines its performance and security in many ways. Therefore, to address the limitations of different blockchain systems, several existing as well novel consensus algorithms have been introduced. A systematic analysis of these algorithms will help to understand how and why any particular blockchain performs the way it functions. Towards this aim, there are a number of existing works that have surveyed and reviewed a number of consensus algorithms. However, all these works have some major shortcomings. For example, the factors upon which the consensus algorithms have been analysed are not comprehensive. Importantly, a wide range of consensus algorithms utilised in public blockchain systems supporting mainly crypto-currencies have different variants. Such variants and their internal mechanisms utilised in many existing crypto-currencies have not been considered at all. This article fills these gaps by analysing a wide range of consensus algorithms leveraged in different public blockchain systems using a comprehensive taxonomy of properties. We have also analysed more than a hundred top crypto-currencies belonging to different categories of consensus algorithms to understand their properties and implicate different trends in these crypto-currencies. Finally, we have presented a decision tree of the reviewed algorithms to be used as a tool to test the suitability of consensus algorithms for a particular application under different criteria.

近年来，加密货币（一种分散的数字货币形式）作为一种替代支付方式已经非常流行。它们以称为区块链的突破性技术为基础它广泛使用了分布式计算领域的许多密码机制和其他高级技术。这项区块链技术已受到全球学术界，行业和政府的无与伦比的关注，被认为具有破坏货币以外的多个应用领域的潜力，触及我们生活的所有领域。对其潜力的飞速上涨已经引起了对其在不同应用领域中的用途的广泛探索。这导致了出于各种目的的众多区块链系统。但是，这些区块链系统中的许多系统都存在与性能和安全性相关的严重缺陷，需要先解决这些缺陷，然后才能实现大规模采用。任何区块链系统的关键组成部分是其底层共识算法，该算法以多种方式决定其性能和安全性。因此，为了解决不同区块链系统的局限性，已经引入了几种现有的以及新颖的共识算法。对这些算法的系统分析将有助于了解任何特定区块链如何以及为何执行其运行方式。为了实现这一目标，已有许多现有作品对许多共识算法进行了调查和审查。但是，所有这些作品都有一些主要的缺点。例如，分析共识算法的因素并不全面。重要的是，主要支持加密货币的公共区块链系统中使用的广泛共识算法具有不同的变体。完全没有考虑在许多现有加密货币中使用的此类变体及其内部机制。本文通过使用广泛的属性分类法分析不同公共区块链系统中利用的广泛共识算法来填补这些空白。我们还分析了属于共识算法不同类别的一百多种顶级加密货币，以了解它们的特性并暗示这些加密货币的不同趋势。最后，我们提出了经过审查的算法的决策树，将其用作工具来测试共识算法对不同标准下特定应用的适用性。本文通过使用广泛的属性分类法分析不同公共区块链系统中利用的广泛共识算法来填补这些空白。我们还分析了属于共识算法不同类别的一百多种顶级加密货币，以了解它们的特性并暗示这些加密货币的不同趋势。最后，我们提出了经过审查的算法的决策树，将其用作工具来测试共识算法对不同标准下特定应用的适用性。本文通过使用广泛的属性分类法分析不同公共区块链系统中利用的广泛共识算法来填补这些空白。我们还分析了属于共识算法不同类别的一百多种顶级加密货币，以了解它们的特性并暗示这些加密货币的不同趋势。最后，我们提出了经过审查的算法的决策树，将其用作工具来测试共识算法对不同标准下特定应用的适用性。我们还分析了属于共识算法不同类别的一百多种顶级加密货币，以了解它们的特性并暗示这些加密货币的不同趋势。最后，我们提出了经过审查的算法的决策树，将其用作工具来测试共识算法对不同标准下特定应用的适用性。我们还分析了属于共识算法不同类别的一百多种顶级加密货币，以了解它们的特性并暗示这些加密货币的不同趋势。最后，我们提出了经过审查的算法的决策树，将其用作工具来测试共识算法对不同标准下特定应用的适用性。