Corona

A Corona is a semi-transparent GUI element appearing throughout the Grand Theft Auto series. The corona first appeared in Grand Theft Auto 1 and has appeared in every game since, in some way or form, utilizing a very similar design and the same purpose throughout the entire series.

Description
The corona appears as a cylindrical element with a semi-transparent appearance, which emits a small amount of light at night. They appear in various sizes with different heights and diameters, and some include an additional icon in the center, such as a finishing-line flag, or a vehicle. Most appear vertical, while some air checkpoints may appear horizontal and appear as rings rather than a single cylinder. Typically, the corona is coloured yellow/gold, however various checkpoints, particularly in the HD Universe appear in blue, orange, red and green, too.

Usage
The purpose of the corona varies throughout the series however it mainly acts as a trigger point to activate missions, or as a checkpoint to reach.