| Sample space | S | a list of possible outcomes (make sure they are unique values) |
| A specific event | A, B, C,... | a subcollection of outcomes in S |
| Simple event | A, B, C,... | an event that contains one outcome that cannot be broken down any further |
| Compound event | S | an event that contains more than one outcome |
| Complementary event | A', Ac | an event that contains all outcomes not in the original event (A′ contains all outcomes not in A) |
| Union of 2 events (A or B) | A ∪ B | an event that contains all outcomes in A, B, or both (make sure not to double-count outcomes) |
| Intersection of 2 events (A and B) | A ∩ B | an event that contains only the outcomes in both A and B |
| The probability of A | P(A) | the chance of event A has occured: P(A) = number of outcomes in A / number of equally-likely outcomes in S |
| A belongs to B | A ∈ B | |
| Null set | ∅ | Empty set |
| Universal set | Ω, S | a set that contains all the elements or objects of other sets, including its own elements |
| Atom, singleton | ω, s | |
| Proper subset | ⊂ | A ⊂ B if set B contains at least one element that is not present in set B |
| Subset | ⊆ | A ⊆ B if all elements of A are also elements of B |