An ignition interlock device is an in-vehicle breath testing system that prevents the car from starting unless the driver provides a breath sample below a set alcohol threshold. Courts or administrative agencies may require installation after a DUI conviction, as a condition for a restricted driving permit, or as part of sentencing. The device typically requires initial installation, periodic calibration, and produces logs that document all start attempts, failed tests, and rolling retests. For Greenville residents, understanding these basics clarifies why the device is required and how it affects daily driving. If you are ordered to use a device, you should complete installation promptly with an approved provider and retain all service and calibration records. These records demonstrate compliance and are often reviewed by courts or licensing authorities when considering further sanctions or permit reinstatement. Keeping accurate documentation and following provider instructions reduces the likelihood of disputed reports leading to additional penalties and helps you maintain mobility for work and family obligations while meeting legal requirements.