This report provides background information on the many dimensions of bias, uncertainty and information shortcomings that affect the conservation of poorly known species in particular and hence biodiversity in general. It was prepared as an issues paper for a workshop in 2016, and the workshop led to the subsequent development of an options paper (Rumpff 2018) that evaluated the costs, benefits and relative efficacy of a range of mechanisms that could address the issues affecting poorly known but imperilled species, and deliver better conservation outcomes for them.