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 loop classification and populations, and then describes the morphology of coronal loops, its relationship with the magnetic field, and the concept of loops as multi-stranded structures. The following part of this section is devoted to the characteristics of the loop plasma and of its thermal structure in particular, according to the classification into hot, warm, and cool loops. Then, temporal analyses of loops and the observations of plasma dynamics and flows are illustrated. In the modeling section some basics of loop physics are provided, supplying some fundamental scaling laws and timescales, a useful tool for consultation. The concept of loop modeling is introduced and models are distinguished between those treating loops as monolithic and static, and those resolving loops into thin and dynamic strands. Then, 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. Finally, a brief discussion about stellar X-ray emitting structures related to coronal loops is included and followed by conclusions 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础。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（除了提供有关恒星回路信息的非太阳能回路）之类的话题。观察部分讨论了环的分类和种群，然后描述了冠状环的形态，其与磁场的关系以及环为多链结构的概念。本节的以下部分根据热，暖和冷回路的分类，专门介绍回路等离子体的特性及其热结构。然后，说明了循环的时间分析以及等离子体动力学和流动的观察结果。在建模部分中，提供了一些循环物理学的基础知识，并提供了一些基本的缩放定律和时间表，这是进行协商的有用工具。介绍了循环建模的概念，并区分了将循环视为整体和静态循环的模型，以及将循环分解为细小和动态链的模型。然后，将进行更具体的讨论，以对环路的精细结构和沿环路流动的等离子体进行建模。特别注意回路加热的问题，分别讨论了波（AC）和脉冲（DC）加热。最后，对与冠状环相关的恒星X射线发射结构进行了简短讨论，并附有结论和未解决的问题。