An intranet is an internal-facing network or portal — for employees, not customers. Intranets host HR resources, company news, internal documentation, and employee tools. While customer portals and intranets share some technical infrastructure, they serve fundamentally different audiences with different access controls, branding, and workflows.
Modern intranet platforms include Microsoft SharePoint, Confluence, Notion, and Happeo. Customer portals and intranets are usually separate systems even though some vendors (Salesforce, Microsoft, Liferay) offer products that span both.
See also: extranet.