WIMPs initially originated as an outcome of string theory. Scientists then started looking at them as dark matter candidates. WIMPs are attractive candidates because they show up in two theories in physics and attempt to solve more than one question. Scientists study the hypothetical WIMPs by attempting to sense them in underground detectors as they pass through the earth and by trying to creat them in accelerators. WIMPs are very massive particles that scientists proposed as a component of dark matter. They interact weakly with normal matter. Scientists predict that they go back to the beginning of the universe 13.7 billion years ago, but scientists did not discover enough of them account for dark matter. WIMPs include heavy neutrinos which have been strong candidates for dark matter. 
WIMPs interact weakly with normal matter and are very difficult to detect. Most of them pass through earth without getting stuck or without colliding with normal matter like materials on earth. If particles do not collide with normal matter like with a detector they cannot be sensed. WIMPs need highly sensitive equipment and research has not reached the ability to detect them. The large underground xenon detector (LUX) in South Dakota is the major instrument for studying WIMPs and it hasn't detected a WIMP yet since 2014. Scientists cannot be exactly sure of the existence of WIMPs if they cannot detect them.