In recent years there has been much interest in non-Hermitian Hamiltonians with real eigenvalues. In particular, PT-symmetric Hamiltonians H, i.e., , where P is the parity operator and T is the time reversal operator, have been conjectured to have a real spectrum except when the symmetry is spontaneously broken. It is also known that PT symmetry is not a necessary condition for the occurrence of real eigenvalues. Then, -pseudo-Hermiticity, i.e., , was introduced to establish the mathematical relation with PT symmetry and explored the basic structure responsible for the reality of the spectrum of non-Hermitian Hamiltonians. Because of intrinsic interest and their applications in condensed matter, quantum optics and others, we study the pseudo-Hermitian interactions in both non-relativistic and relativistic quantum mechanics by considering several examples about delocalization transition in superconductors and spin-orbit coupling in semiconductors. In addition, the pseudo-supersymmetry and boson sea are studied. Finally, the PT-symmetric quantum field theory, Klein-Gordon-type field and quantum cosmology are discussed, too. Keywords: Pseudo unitarity; Pseudo-Hyper-virial theorem; Pseudo-probability current density; Pseudo-supersymmetry; Boson sea; Abnormal pseudo-Hermitian fermion; PT-symmetric quantum field theory; Klein-Gordon-type field.