A V5C, or vehicle registration certificate, is the DVLA document that records the registered keeper of a vehicle and its details. Often called the logbook, it proves who is responsible for a vehicle but is not proof of legal ownership.
In one line: A V5C, or logbook, is the DVLA certificate naming the registered keeper of a vehicle and recording its details.
How a V5C works
The V5C is issued under the Vehicle Excise and Registration Act 1994 and lists the keeper, make, model, engine and registration. It is used to tax a vehicle, notify a sale and update the DVLA when details change.
When a car is sold, the seller completes the relevant section and notifies the DVLA, who then issue a new V5C to the buyer, usually within a few weeks. For example, a buyer paying 6,000 GBP for a used car receives a fresh V5C in their name confirming they are now the registered keeper.
Keeping the V5C up to date matters because the DVLA sends fines, reminders and enforcement notices to the registered keeper on record.
Registered keeper vs owner
The V5C names the registered keeper, the person responsible for taxing the vehicle and answering for offences, which is not necessarily the legal owner. A company car driver is often the keeper while the finance firm or employer owns the vehicle.
Because the V5C is not a title document, possession of it alone does not prove ownership, a point that matters in disputed or fraudulent sales.
Primary source: GOV.UK: Vehicle registration certificate (V5C)