Which phrase best describes ArcGIS Online?

ArcGIS Online is best described as a cloud-based geographic information system. This platform enables users to create, share, and manage geographic content over the internet, allowing for accessibility from anywhere with an internet connection. The cloud-based nature of ArcGIS Online offers several advantages, including real-time collaboration, automatic updates, and the ability to access large datasets and powerful GIS tools without the need for extensive local hardware or software installation.

The other descriptions do not accurately capture the essence of ArcGIS Online. While a localized geographic information system focuses on data and tools installed on a specific local machine or network, ArcGIS Online operates entirely in the cloud. A desktop-based geographic information system typically refers to software applications installed on a personal computer, which is not representative of ArcGIS Online's functionality or delivery model. Lastly, a mobile device-based geographic information system would refer to GIS applications specifically designed for mobile platforms, whereas ArcGIS Online is designed to be used across various devices, including computers and mobile devices, but fundamentally operates as a cloud-based service.