Hydrogen tails, plumes, clouds and filaments
  Here I present a brief review of interacting galaxy systems with extended low
surface brightness (LSB) hydrogen tails and similar structures. Typically found
in merging pairs, galaxy groups and clusters, HI features in galaxy
surroundings can span many hundreds of kpc, tracing gravitational interactions
between galaxies and ram pressure forces moving through the intra-group/cluster
medium. Upcoming large HI surveys, e.g., with the wide-field (FOV = 30 square
degrees) Phased Array Feeds on the Australian SKA Pathfinder (ASKAP), will
provide a census of LSB structures in the Local Universe. By recording and
comparing the properties (length, shape, HI mass, etc.) of these observed
structures and their associated galaxies, we can - using numerical simulations
- try to establish their origin and evolutionary path.
