Let's look at this carefully. First, there are some new symbols to digest: “\(\N\)” is the symbol usually used to denote that natural numbers, which we will take to be the set \(\{0, 1, 2, 3, \ldots\}\text{.}\) Next, the colon, “:”, is read such that; it separates the elements that are in the set from the condition that the elements in the set must satisfy. So putting this all together, we would read the set as, “the set of all \(x\) in the natural numbers, such that there exists some \(n\) in the natural numbers for which \(x\) is twice \(n\text{.}\)” In other words, the set of all natural numbers, that are even. Here is another way to write the same set.