In short
Approved Driving Instructor — a UK driving instructor licensed by the DVSA to charge for driving lessons.
ADI stands for Approved Driving Instructor. It is the UK qualification, awarded by the Driver and Vehicle Standards Agency (DVSA), that licenses an instructor to charge for driving lessons.
To qualify as an ADI a candidate must pass three exams: a theory test, a driving ability test, and an instructional ability test. Once qualified, the instructor displays a green ADI badge in their car. A pink badge means the instructor is a Potential Driving Instructor (PDI) — still in training but legally able to teach.
When you book a lesson with an ADI you are protected by DVSA-set standards on conduct and competence. ADI status is what Driving Routes verifies when an instructor contributes routes to the platform.