Directional Drilling is defined as the practice of controlling the direction and deviation of a wellbore to a predetermined underground target or location. This section describes why directional drilling is required, the sort of well paths that are used, and the tools and methods employed to drill those wells.

Listed are some of the major applications of directional drilling:

• Multiple wells from a single location.
• Inaccessible surface locations.
• Multiple target zones.
• Sidetrack.
• Fault drilling.
• Salt-dome exploration.
• Relief-well drilling.
• River-crossing applications.