Observational features to distinguish Kerr black hole from their mimickers’

It is evident from the literature that the final fate of a collapsing star can be a hidden or a visible singularity. The question then arises: How can these two distinct types of singularities be dis tinguished from one another? In this presentation, I will discuss the observational properties of compact astrophysical objects, with or without an event horizon. First, I will discuss the precession of test particles as they orbit these compact objects. Another aspect is the shadow cast by a black hole or a naked singularity. Mainly, I will discuss the mechanisms governing the energy extraction from these compact objects and the fundamental conditions for the occurrence of such phenomena. Concluding this we will discuss open questions within this domain.