I wil review some aspects of quantum entanglement entropy in high energy physics. I will discuss how entanglement emerges naturally in proton-proton and deep inelastic scattering at high energies, where string-bit dynamics, saturation and Pomeron exchange can be interpreted through entangled density matrices and thermal-like entropy production. Using worldline and worldsheet instanton methods, together with holographic and string based approaches, I show how coherent quantum processes generate rapid apparent thermalization and entropy growth in hadron collisions. Applications to low-x DIS, multiplicity distributions, KNO scaling, and Schwinger pair production in QED2 will be discussed.