OTC stands for other than collision, also known as comprehensive coverage, a type of physical damage coverage. Other than collision is an optional physical damage coverage, which helps protect your vehicle in case of theft, vandalism, glass damage, damage from hitting an animal, fire, floods and weather-related damage.
It's called "other than collision" in reference to collision coverage, which covers damage to your car when your car hits, or is hit by, another vehicle, or other object. It does not matter who is at fault in the accident that damages your vehicle; you can make a claim under collision, but will pay your deductible.
A car insurance coverage package including both comprehensive and collision coverage is often referred to as "full coverage."
If you aren't sure whether to buy collision or comprehensive coverage, use our tool "How much car insurance do I need?" to see what's best for your situation.