Your phone was buzzing and you just had to check the text. Next thing you know, you miss a light change and plow into the car in front of you. Nobody seems seriously hurt at first, so you trade information with the other driver, apologize, and soon return to the preoccupations that led to the accident.
A fender bender refers to a minor collision, so generally speaking these are resolved through auto insurance claims. Technically speaking, these are tiny accidents. But molehills can become mountains with time and you may find yourself sued for negligence due to an injury caused by your fender bender.