ELD
The electronic logging device that records your driving hours automatically to keep you compliant with hours-of-service rules.
An ELD is an electronic logging device. It plugs into the truck and records your driving time automatically, replacing the old paper logbook. Most commercial drivers are required to run one, and it tracks your hours of service so the record of when you drove and when you rested is made for you.
The point is hours-of-service compliance. Federal rules limit how many hours you can drive in a day and in a week, and how much rest you need in between. The ELD keeps that clock honestly, which protects you in an inspection and keeps you from accidentally running over your hours.
An ELD tracks hours, not fuel tax or pay. It is a different system from your IFTA mileage and your invoicing, though the miles and the driving time both come from the same trips. It handles the safety clock so you can focus on the load.
Related: USDOT number, layover.