In current global market, it is more usual to have to implement an SAP solution across different countries. Here there are some useful links about globalization and localization in SAP:
Information about globalization.
Information about localization in SAP. It contains useful links.
SAP Legal Changes
Information about legal changes in SAP.
SAP Country Legal Changes (CLC)
Legal Changes specific to SAP HCM.
SAP Country versions
Information about the Country versions available in SAP.
SAP Globalization Knowledge Base
SAP GKB was replaced by SAP Localization > Countries.