Flow-based methods have been recognized as excellent tools for the automation and miniaturization of the main stages of chemical analysis. Since its inception, flow-based analysis has dramatically transformed the way that sample analysis is handled. This article highlights some of the most important developments in flow analysis and describes different flow systems and their fundamental principles. Recent applications of flow analysis with various detection methods are also presented. Special attention is paid to the automation of sample pretreatment, including separation and preconcentration procedures based on various flow systems. Relative advantages and disadvantages of the various flow methods are discussed.