  Hydrodynamical simulations are increasingly able to accurately model physical
systems on stellar, galactic, and cosmological scales, however, the utility of
these simulations is often limited by our ability to directly compare them with
the datasets produced by observers: spectra, photometry, etc. To address this
problem, we have created Trident}, a Python-based, open-source tool for
post-processing hydrodynamical simulations to produce synthetic absorption
spectra and related data. Trident} can (i) create absorption-line spectra for
any trajectory through a simulated dataset mimicking both background quasar and
down-the-barrel configurations, (ii) reproduce the spectral characteristics of
common instruments like the Cosmic Origins Spectrograph, (iii) operate across
the ultraviolet, optical and infrared using customizable absorption line lists,
(iv) trace simulated physical structures directly to spectral features, (v)
approximate the presence of ion species absent from the simulation outputs,
(vi) generate column density maps for any ion, and (vii) provide support for
all major astrophysical hydrodynamical codes. The focus of Trident's
development is for using simulated datasets to better interpret observations of
the circumgalactic medium (CGM) and intergalactic medium (IGM), but it remains
a general tool applicable in other contexts.
