In a deck of 52 cards, there are 4 aces (one for each suit). The probability of selecting an ace is:
\[
P(\text{getting an ace}) = \frac{\text{Number of favorable outcomes}}{\text{Total outcomes}} = \frac{4}{52} = \frac{1}{13}
\]
Thus, the probability is \( \frac{1}{13} \).