Photoionization and photodissociation regions
Radiative processes and nebular diagnostics
Neutral hydrogen: Lyman series absorption, resonance lines
Molecular emission
Dust properties and astrochemistry
Magnetic fields in diffuse media
Continuum processes: Thermal emission from gas and dust
Continuum processes: Nonthermal emission: synchrotron, gamma rays
Turbulence and dynamical processe