The application of scientific knowledge for practical purposes is known as technology.It refers to the making, usage and knowledge of tools, techniques, systems or methods of organization in order to solve a problem or serve some purpose and also to help us in our day to day activities.
A gadget is a small technological object (such as a device or an appliance) that has a particular function. The use of such gadgets is termed as gadgetism. So officially it seems that usefullness and purpose of gadgets are the defining characters. No so much technology etc.The origins of the word "gadget" trace back to the 19th century.
