We provide a brief overview of this work. Firstly, we introduce the language of NF theory and all the fundamental concepts on which it is based. Then, we define basic operations on sets and introduce sets of significance such as the set of natural numbers and the set of cardinal numbers. We have attempted, at least briefly, to convey the beauty and elegance of NF theory based on its simplicity. Its magnitude would not be questionable if we did not have the second chapter, which, on the other hand, casts a shadow over the theory itself-explaining, hopefully in sufficient detail, why it has not caught on, at least not in its original form. The weight of Specker’s theorem lies not only in its proof (in spite of its size) but in the consequences its assertion has on the theory. However, as hinted at in the third chapter, the theory is intriguing and interesting enough that such a blow does not break it and send it to oblivion. Only a few changes in the formulation of the theory’s language result in multiple versions of the theory that are not only relatively consistent with previously accepted ones in mathematics, but also remain consistent when adding the axiom of choice and the axiom of infinity—two claims irreconcilable in pure NF.