Show pagesourceBacklinksCite current pageExport to PDFFold/unfold allBack to top Share via Share via... Twitter LinkedIn Facebook Pinterest Telegram WhatsApp Yammer Reddit TeamsRecent ChangesSend via e-MailPrintPermalink × Validation Confirming that a product or service meets the needs of its users. External validation Internal validation. validation.txt Last modified: 2025/04/29 20:25by 127.0.0.1