The separability problem is one of the basic and emergent problems in present and future quantum information processing. The latter focuses on information and computing based on quantum mechanics and uses quantum bits as its basic information units. In this paper we present an overview of the progress in the separability problem in bipartite systems, more specifically in two quantum bits (qubits) system, from the criterion based on the Bell’s inequalities in 1964 to the Li-Qiao Criterion and the enhanced entanglement criterion based on the symmetric informationally complete positive operator valued measures (SIC POVMs) in 2018.