General liability covers a business owner from risk of loss "due to damage or injury (caused by negligence or acts of omission) during performance of his or her duties or business" according to the website Business Dictionary. Injury or damage could occur on site or off site during the performance of business services.
General liability coverage is vast and includes protection for employees acting on behalf of the business, anyone else legally connected to your business, legal defense expenses during lawsuits, and medical care for the injured or ill claimant.
Your cost for general liability protection is based on the potential risk of payout and amount. Businesses that conduct higher-risk operations and are more likely to face suit would pay more than a less risky operation. Rates in some states may also be higher based on precedent for higher damage awards to plaintiffs.