The document discusses statically determinate and indeterminate structures. A determinate structure is one where reactions and internal forces can be determined through static equilibrium equations alone. An indeterminate structure has more unknown reactions or internal forces than equations. The degree of static indeterminacy is the number of redundant unknowns. Continuous beams are internally determinate but can be externally indeterminate. The example beam has a degree of indeterminacy of 1.