Explore a comprehensive lecture on the flux tube spectrum and world-sheet axion in non-Abelian gauge theories. Delve into theoretical expectations from Goddard-Goldstone-Rebbi-Thorn and Effective String Theory, followed by detailed lattice calculations including setup, correlation functions, and excitation spectrum extraction. Examine operator construction techniques, focusing on quantum numbers and lattice operators. Analyze results for both 2+1 and 3+1 dimensional cases, covering various excited states and the k=2 string. Gain insights into color confinement, chromoelectric flux tubes, and their role in the large N limit of gauge theories, as presented by Andreas Athinodorou from the Cyprus Institute during the Confinement, Flux Tubes, and Large N conference at the Kavli Institute for Theoretical Physics.