To get straight to the point, if your car is leaking a little bit of water, then it's probably just excess moisture from the air conditioning system. However, it the fluid is a dark or bright color, thick in its consistency or has any other distinguishing characteristics, then you should take it to a mechanic or have it towed immediately.
One of the most dangerous fluid leaks is fuel. If your vehicle is leaking gasoline, then do not drive it. It's a sign that your fuel pump or gas tank is leaking, so you should have it towed to a mechanic immediately. Driving a vehicle that's leaking fuel almost never causes a fire, but there's still a risk, so we'd recommend having the problem taking care of immediately. Besides, driving on a tank that's leaking gas or diesel will most certainly hurt your wallet.