Ordered sets can be thought of as categories with particularly tidy arrow structures. We will first look at totally ordered sets. We will give the definition of an ordered set as a special kind of category, and then unravel that to give the direct definition as a set with extra structure, the latter being the definition that is usually given when this topic is covered before category theory. Examples include the natural numbers ordered by size. We will explore features that cause a category to fail to be an ordered set, looking at the features visually and also formally. We then generalize to partially ordered sets, again giving the definition as a special kind of category and then as a set with structure. Examples include the factors of any fixed number, ordered by the relation “is a factor of”.