String spectra comprise infinitely many physical states of arbitrarily high mass and spin, the presence of all of which is crucial to the good UV behaviour of string scattering amplitudes. Yet what do all these states look like? In this seminar, we will discuss a covariant and efficient technology of constructing entire string trajString spectra comprise infinitely many physical states of arbitrarily high mass and spin, the presence of all of which is crucial to the good UV behaviour of string scattering amplitudes. Yet what do all these states look like? In this seminar, we will discuss a covariant and efficient technology of constructing entire string trajectories deeper in the open (super)string spectrum, the computation of their scattering amplitudes, as well as work to appear on the closed string. The aim of this direction is to attempt to shed light on aspects of the underlying nature of string theory per se.ectories deeper in the open (super)string spectrum, the computation of their scattering amplitudes, as well as work to appear on the closed string. The aim of this direction is to attempt to shed light on aspects of the underlying nature of string theory per se.