Every home as a main water shutoff. It's typically located on a perimeter wall where the water enters your house. If you have a leak or need to turn off the water for any reason, you'll need to know where it is and how to close this valve. Turning the valve to the right (some valves have a lever that will need to be moved to a 90 degree angle from the pipe) will shut off the water to the entire house, even the outside spigots.
It's never a bad idea to turn off the water if you are leaving on a long vacation, or are going away from an extended length of time, to prevent potential leaks from turning into a basement full of water. When you return, turn the water back on slowly and be ready for some bursts of water to come out of the faucets until the lines are running again.