A limited liability company is a creature of state statute. It comes into existence when articles of organization are accepted by a state filing office, and it continues to exist as long as the owner keeps up with that state's renewal requirements. Owners are called members, and an LLC can have one member or many.
The two features that made the form popular are limited liability and flexible taxation. Members are generally not personally responsible for company debts, and profits pass through to the members' own tax returns unless the entity elects corporate treatment. The trade-off is discipline: mixing personal and business money can put the liability shield at risk.