Coronal loops are the building blocks of the X-ray bright solar corona. They owe their brightness to the dense confined plasma, and this review focuses on loops mostly as structures confining plasma. After a brief historical overview, the review is divided into two separate but not independent parts: the first illustrates the observational framework, the second reviews the theoretical knowledge. Quiescent loops and their confined plasma are considered and, therefore, topics such as loop oscillations and flaring loops (except for non-solar ones, which provide information on stellar loops) are not specifically addressed here. The observational section discusses the classification, populations, and the morphology of coronal loops, its relationship with the magnetic field, and the loop stranded structure. The section continues with the thermal properties and diagnostics of the loop plasma, according to the classification into hot, warm, and cool loops. Then, temporal analyses of loops and the observations of plasma dynamics, hot and cool flows, and waves are illustrated. In the modeling section, some basics of loop physics are provided, supplying fundamental scaling laws and timescales, a useful tool for consultation. The concept of loop modeling is introduced and models are divided into those treating loops as monolithic and static, and those resolving loops into thin and dynamic strands. More specific discussions address modeling the loop fine structure and the plasma flowing along the loops. Special attention is devoted to the question of loop heating, with separate discussion of wave (AC) and impulsive (DC) heating. Large-scale models including atmosphere boxes and the magnetic field are also discussed. Finally, a brief discussion about stellar coronal loops is followed by highlights and open questions.

中文翻译：

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冠状Loop：局限血浆的观察和建模

日冕环是X射线明亮的日冕的基本组成部分。它们的亮度归因于稠密的封闭等离子体，而本篇评论主要集中在环路作为封闭等离子体的结构上。在简短的历史概述之后，本综述分为两个独立但并非独立的部分：第一部分说明了观测框架，第二部分回顾了理论知识。考虑了静态回路及其受限的等离子体，因此，这里不专门讨论诸如回路振荡和喇叭形回路（非太阳能除外，它们提供了有关恒星回路的信息）之类的主题。观察部分讨论冠状loop的分类，种群和形态，其与磁场的关系以及strand的绞合结构。根据热，暖和冷回路的分类，本节将继续介绍回路等离子体的热特性和诊断。然后，说明了循环的时间分析以及对等离子体动力学，热流和冷流以及波的观察。在建模部分中，提供了一些循环物理学的基础知识，提供了基本的缩放定律和时间表，这是进行协商的有用工具。引入了循环建模的概念，并将模型分为将循环视为整体和静态的模型，以及将循环分解为细线和动态链的模型。更具体的讨论涉及对回路的精细结构和沿回路流动的等离子体进行建模。特别关注回路加热的问题，另外讨论了波式（AC）和脉冲式（DC）加热。还讨论了包括大气箱和磁场在内的大型模型。最后，简短讨论恒星冠状loop，之后是重点和开放性问题。