Fabrics that purify water using nothing but the sun as energy source. Clothes that can take an ECG or become cool at extreme temperaturas are known as Smart textiles. Smart Textiles‖ refers to a broad field of studies and products that extend the functionality and usefulness of common fabrics. Smart Textiles are defined as textile products such as fibers and filaments, yarns together with woven, knitted or non-woven structures, which can interact with the environment/user. The convergence of textiles and electronics (e-textiles) can be relevant for the development of smart materials that are capable of accomplishing a wide spectrum of functions, found in rigid and non-flexible electronic products nowadays. Smart Textiles will serve as a means of increasing social welfare and they might lead to important savings on welfare budget. They integrate a high level of intelligence and can be divided into three subgroups: 1) Passive smart textiles: only able to sense the environment/user, based on sensors; 2) Active smart textiles: reactive sensing to stimuli from the environment, integrating an actuator function and a sensing device; 3) Very smart textiles: able to sense, react and adapt their behavior to the given circumstances.