Coronal loops form the basic structure of the lower corona and transition region of the Sun. These highly structured and elegant loops are a direct consequence of the twisted solar magnetic flux within the solar body. The population of coronal loops can be directly linked with the solar cycle; it is for this reason coronal loops are often found with sunspots at their footpoints. The upwelling magnetic flux pushes through the photosphere, exposing the cooler plasma below. The contrast between the photosphere and the solar interior gives the impression of dark spots, or sunspots.

A coronal loop is magnetic flux fixed at both ends, threading through the solar body, protruding into the solar atmosphere. They are ideal structures to observe when trying to understand the transfer of energy from the solar body, through the transition region and into the corona.

Many scales of coronal loops exist, neighbouring open flux tubes that give way to the solar wind and reach far into the corona and heliosphere. Anchored in the photosphere (a rigid, line-tied, anchor is assumed where the high-β, external plasma holds the loop footpoints in place), coronal loops project through the chromosphere and transition region, extending high into the corona.