This biennial conference is the main international forum for both fundamental and applied works dealing with processes related to the formation of the spectral line profiles and with their use for diagnostic purposes. On the fundamental side, the study of the line profiles reveals the underlying atomic and molecular interactions. On the practical side, the line profiles are employed as powerful diagnostic tools for various media, such as neutral gases, technological gas discharges, magnetically-confined plasmas for fusion, laser- and Z-pinch-produced plasmas, astrophysical plasmas, and planetary atmospheres.