Multisensor systems for liquid analysis based on chemical sensor arrays and pattern recognition, which are now widely known as 'electronic tongues', represent one of the most rapidly emerging and exciting fields of non-classical analytics during the last decade. This chapter presents an overview of the research and development of electronic tongue systems and describes various sensors, sensor arrays, and their numerous applications. A sound basis for electronic tongues was provided by the extensive development of well-known selective sensors, especially electrochemical, and biological inspirations originating from sensory systems of mammalians. The up-to-date achievements of various scientific groups working in this field are reviewed. The performance of electronic tongues in the tasks of recognition (classification, identification, discrimination) of multicomponent media is considered. A useful option of multicomponent quantitative analysis with the help of electronic tongues is also reported. The correlation between the output of an electronic tongue and human sensory assessments of food flavor made by taste panel opens up an exciting possibility of measuring and quantifying the taste and flavor of foods. Application areas of the electronic tongue systems, including quality control of foodstuffs, clinical, industrial and environmental analysis, are surveyed. Future prospects for research and development of electronic tongues are discussed.