Unique word orthogonal frequency division multiplexing (UW-OFDM) is a novel data transmission scheme where the guard interval is implemented as a deterministic sequence, the so-called unique word. The UW is generated by introducing a certain level of redundancy in the frequency domain. This can either be done by appropriately loading a number of dedicated subcarriers with redundant symbols instead of data or by distributing the redundancy over all subcarriers. The first approach can be interpreted as designing a systematic Reed Solomon (RS) code over the field of complex numbers, while the latter concept introduces a non-systematic RS code. The UW can advantageously be exploited for synchronization and parameter estimation tasks (e.g. CFO estimation, channel tracking). Furthermore, due to the introduced RS code properties UW-OFDM features and outstanding bit error ratio (BER) performance especially in frequency selective channels. UW-OFDM opens up many research opportunities in information and coding theory, signal processing and communications technology.