NTRU is one of the few public key cryptosystems which is supposedly quantum-computer resistant. Its security is based on the presumed difficulty of a lattice problem, namely, the shortest vector problem. This research paper describes the NTRU cryptosystem and its cryptanalysis. Finally, a comparison of the performance of the NTRU with other public key crytosystems such as RSA, Elliptic Curve, and McEliece, is presented.