Blockchain technology is affected by massive limitations in scalability with consequent repercussions on performance. This discussion aims at analyzing the state of the art of current available Layer II solutions to overcome these limitations, both focusing on theoretical and practical aspects and highlighting the main differences among the examined frameworks. The structure of the work is based on three major sections. In particular, the first one is an introductory part about the technology, the scalability issue and Layer II as a solution. The second section represents the core of the discussion and consists of three different subsections, each with a detailed examination of the respective solution (Lightning Network, Plasma, Rollups); the analysis of each solution is based on how it affects five key aspects of blockchain technology and Layer II: scalability, security, decentralization, privacy, fees and micropayments (the last two are analyzed together given their high correlation). Finally, the third section includes a tabular summary, followed by a detailed description of a use-case specifically thought for a practical evaluation of the presented frameworks. The results of the work met expectations: all solutions effectively contribute to increasing scalability. A crucial clarification is that none of the three dominates the others in all possible fields of application, and the consequences in adopting each, are different. Therefore, the choice depends on the application context, and a trade-off must be found between the aspects previously mentioned.

翻译：讨论的目的是分析现有第二层现有解决办法的先进程度,以克服这些限制,既注重理论和实践方面,又强调所审查的框架之间的主要差异。工作结构以三个主要部分为基础。特别是,第一部分是关于技术的导言部分、可调整性问题和第二层作为解决办法。第二节是讨论的核心,由三个不同的分节组成,每个分节详细审查各自的解决办法(ightning Network, Plasma, Rollups);对每一种解决办法的分析都基于它如何影响块链技术和第二层的五个关键方面:可扩展性、安全性、权力下放、隐私、收费和微额支付(后两个部分是根据其高度关联性一起分析的)。最后,第三节包括一个表格摘要,然后是详细描述具体考虑实际评价所提出的框架的使用情况。工作的结果达到了预期:所有解决办法都有效地有助于增加可调整性。一个关键的解释是,三个方面没有一项以前在贸易中发现的不同方面,因此,每个方面都取决于在贸易中发现的不同方面。