1. A “set” is a collection of objects known as “elements”, surrounded by curly braces “{}” and separated by commas or indicated by using, “set builder notation.”
2. When using “set builder notation”, the pipe or vertical line “|” is equivalent to saying, “such that”.
3. Likewise, the element symbol “∈” is equivalent to saying, “is an element of” and “∉” meaning, “is not an element of”.

Example: ℕ = {x | x is an integer greater than 0}, verbally stated as, “the set ‘ℕ’ equals ‘x’, such that ‘x’ is an integer greater the zero, then 5 ∈ ℕ, but -5 ∉ ℕ.