The dimension of Euclidean n -space E is n. When trying to generalize to other types of spaces, one is faced with the question "what makes E n -dimensional?" One answer is that to cover a fixed ball in E by small balls of radius ε, one needs on the order of ε such small balls. This observation leads to the definition of the Minkowski dimension and its more sophisticated variant, the Hausdorff dimension, but there are also other answers to that question. For example, the boundary of a ball in E looks locally like E and this leads to the notion of the inductive dimension. While these notions agree on E, they turn out to be different when one looks at more general spaces.