Abbreviation of “electromagnetic spectrum,” which is usually taken to mean the range of electromagnetic frequencies (or wavelengths), which can be used to transmit radio signals. Spectrum is regarded as a public commons, which governments then allocate through a licensing process to particular users. Thereafter, allocated spectrum is usually regarded as a property right or quasi-IP right.  One method of allocation is auctioning of parts of the available spectrum, for example to cellular telephone operators—in the latter case the operators in recent cellular auctions in the U.S. and Europe are regarded as having catastrophically overbid (overpaid) for spectrum.