What aspect of a web map can be customized in ArcGIS Online?

In ArcGIS Online, the customization of a web map primarily revolves around layer visibility and appearance. This means you can alter how layers in your map are displayed, which includes changing symbology, colors, and the order in which layers appear. Customizing these aspects allows users to present the data in a way that is more meaningful and visually compelling for end-users or specific projects.

You can adjust various elements such as the transparency of layers, labels, and even apply different styles to represent the data effectively. This feature is particularly useful for emphasizing specific data trends or making the map more accessible to users with diverse needs.

The other areas mentioned do not offer the same level of customization in a web map context. Data sources relate to the origin of the data utilized within the map, but once the data is sourced, it is the visualization settings that users frequently adjust. Geography refers more to the actual spatial context and boundaries represented on the map, which is generally set by the nature of the data rather than customizable per se. Network settings, on the other hand, pertain to system configurations for connectivity and performance, which also fall outside the scope of visual customizations within ArcGIS Online web maps.