Nature-inspired methods are finding more and more practical applications. At present, one can observe a strong development of these techniques associated with the design of new algorithms or new modifications of currently known algorithms. Among the whole family of nature-based optimization algorithms, swarm intelligence algorithms take a special place. In these algorithms, the main focus is on cooperation between individual solutions, which results in the broader perspective of the algorithm to reach better and better solutions. This chapter presents a short overview of swarm intelligence algorithms (SIAs). The basic algorithm derived from this family, which is the particle swarm optimization algorithm, is shown in detail. The chapter presents the popularity of SIAs based on publicly available scientific databases such as Springer, Google Scholar, Science Direct, IEEE Explore and Web of Science. The main areas in which the previously indicated algorithms are applied are also presented, and several papers related to engineering applications of swarm intelligence algorithms are briefly discussed. The chapter concludes with a summary.