In the first aspect, the invention provides a fastener which includes a fastening element and an actuating means attached to the fastening element. The fastening element has a flexible beam and an engagement means. The actuating means includes a material, such as shape memory alloy, which contracts when activated. When the material is contracted, the beam moves between an engagement position and a disengagement position. In a second aspect, the invention provides a fastener for use in a network of fasteners. The fastener has address means which serve to distinguish the fastener from the other fasteners in the network. The fastener may be the same as the fastener in the first aspect of the invention, or a different fastener. A network or system of such fasteners is also provided. In a third aspect, the invention provides, in a process for producing product, during which process there are a number of steps in which a first element is releasably fixed to a second element, the use of the fastener in the first aspect or the second aspect of the invention to releasably fix the first element and the second element. The invention also provides a computer system programmed to perform the process of the invention.