Commission J2 seeks to bring together members of the scientific community who study the properties of intergalactic gas and their interactions with galaxies and AGN. The Commission encompasses four research themes: the structure of the Intergalactic Medium, the ultra-violet metagalactic background, the interaction between galaxies and the AGN with the Intergalactic Medium, and the Epoch of Reionization.

The purpose of the Commission is to provide a forum for exchanging information of use to its members specific to the IGM, to coordinate discussions and planning papers with other Commissions relating to the IGM, and to assist in coordinating meetings on the IGM.