When a secured creditor has taken the required steps to perfect his lien, the lien is senior to any liens that arise after perfection. A mortgage is perfected by recording it with the county recorder; a lien in personal property is perfected by filing a financing statement with the secretary of state. An unperfected lien is valid between the debtor and the secured creditor, but may be behind liens created later in time, but perfected earlier than the lien in question. An unperfected lien can be avoided by the trustee.