Force Concealment, also called Force Stealth, is a versatile power that allows skilled Force-users to mask their Force alignment (Light or Dark), their ability to use the Force, or even their entire presence from others who are Force sensitive.
Unlike a lot of other Force powers, Force Concealment can be developed and implemented in a variety of ways. In addition there are many different levels to how well the concealment will work. Forcers gifted with an excellent Force Sense, or who specialize in detecting things through the Force, may be able to see through the concealment depending on the skills of the respective users.
Generally those who have dedicated their lives to perfecting their power in Force Concealment have a much better chance of remaining undetected than those who use it only occasionally. Very skilled users of this ability may also vary their level of concealment at will.