Sigs figs are affected by measurments. "Exact" numbers, like the density of water(because the definition of 1g is the weight of 1ml of water), conversion factors(60 minutes in an hour) and the number of discrete objects(12 pencils, 5 dogs) do not affect them. Accuracy is defined as closeness to the true answer, while precision is defined as consistency in measurments. You can be one and not the other, both, or neither.