Auto Parts Glossary: Key Terms Explained
Parts terminology is full of acronyms. This glossary defines the terms you'll meet when identifying and ordering genuine components.
Core terms
- EPC — Electronic Parts Catalog: the manufacturer's official parts database
- VIN — Vehicle Identification Number: the 17-character code identifying a vehicle
- WMI — World Manufacturer Identifier: the first three VIN characters (maker + country)
- OEM — Original Equipment Manufacturer: the supplier of the original part
- Genuine part — sold in the carmaker's own branded box
- OE-quality — aftermarket part built to equivalent specification
- Supersession — replacement of one part number by a newer one
- Exploded diagram — an assembly drawn out to show every component and its quantity
- Fitment — whether a part matches the exact vehicle build