I'm studying Commutative Algebra and Topology recently. As far as I'm concerned, categories are fundamental in mathematics so I'm particularly fond of algebra in favor of the concept of category. I saw some one says geometry and topology structures are much more interesting than algebra structures. I don't understand it very much. Maybe in my mind all structures are algebraic. Well, maybe when we adopt measures and Cauchy sequences we are entering the field of Analysis, Geometry and Topology? Actually in my heart it is still algebraic. I think continuity doesn't mean non-algebra.