This chapter presented the Sine Cosine Algorithm (SCA), which is a recent meta-heuristics using mathematical equations to estimate the global optima of optimization problems. After discussing the mathematical model, a brief literature review is given covering the most recent improvements and applications of this algorithm. The performance of this algorithm is benchmarked on a wide range of test functions showing the flexibility of SCA in solving diverse problems with different characteristics. The chapter also considers finding an optimal design for a bend photonics crystal that shows the merits of this algorithm is solving challenging real-world problems.