A general contractor, or "GC", is a licensed professional who manages rehab projects. General contractors are responsible for overseeing a renovation project to ensure it is done on time, on budget and to regulatory code.
General contractors work with the client (homeowner, real estate investor) to understand project goals, map out the scope and costs of the project, select and manage sub contractors ("trades"), coordinate permits and code enforcement inspections, and deliver the completed project on time and on budget.
General contractors typically account for 10% to 15% of the total rehab budget. So if your GC quotes $100,000 for a renovation project, then they are likely charging $10,000 to $15,000 for their services.
General contractor license requirements vary by state. Licenses may be required depending on the type of work (i.e. electrical, plumbing, HVAC) and the type of construction funding (i.e. FHA 203k loan). It is always advised that you work with licensed contractors.