Smart or intelligent textiles are those which can sense and then respond to an external stimulus. The stimuli conditions can include heat change, light, sound, ph level, electronic or magnetic currents, moisture or mechanical interaction. Responses are engineered in reaction to the stimulus and these can include thermal, light, electronic outputs, and mechanical movement.
The movement towards standardising smart textile defines that the word smart is interchangeable with intelligent, however a range of other terms and definitions are widely used.
Passive Smart Textiles; Can only sense a stimulus.
Active Smart Textiles: Can sense and react (actuate) to a stimulus.
Ultra smart textiles: Can sense and react to stimuli and adapt themselves to meet the conditions, implementing reasoning.
Clothing with wearable technology are garments with in build technology devices such as music players, they are not specifically classed as smart, these are defined as electronic of E-Textiles.