ArcGIS 10.5 is stable and still used in many organizations, but Esri support for 10.5.x ended in . For new projects or compliance, upgrade to ArcGIS Pro (latest version). However, 10.5 remains an excellent learning platform for classic GIS workflows.
The gateway that allows the server to communicate with existing web infrastructures. Key Capabilities and Features ArcGIS 10.5
The most significant change in 10.5 was the rebranding of the server product family to ArcGIS Enterprise ArcGIS 10
: A central hub for managing and sharing maps, apps, and geographic information within an organization. and geographic information within an organization.