Liner Hanger is similar to casing, is a tool/system that is used to hang a liner in a production well. But it is not run through the full depth of the well, as casing is, A liner hanger allows the liner (casing below the liner hanger) to be suspended in the previous casing string to reduce material cost and provide completion solution options. A seal is required at the top of the liner hanger to prevent transfer of fluid or pressures from either direction.

The purpose of the liner hanger, aside from the structural well construction purpose , is to isolate flow up inside of the liner rather than the annular space which would contribute in the event no liner hanger were set. Liners are used to save on metal costs, as since the pipe does not run to the top, and sometimes on cementing costs (some liners are not cemented). As the name suggests, you use liner hangers to fix liners in place. The feature that distinguishes a liner from a regular casing column is that it starts not at the top of the well, but at some point below ground (usually deeper than 1000m).