A fastener is a hardware

Hardware

Hardware is a general term for equipment such as keys, locks, hinges, latches, handles, wire, chains, plumbing supplies, tools, utensils, cutlery and machine parts. Household hardware is typically sold in hardware stores....

 device that mechanically joins or affixes two or more objects together.

Fasteners can also be used to close a container such as a bag, a box, or an envelope; or they may involve keeping together the sides of an opening of flexible material, attaching a lid

Lid (container)

A lid, also known as a cap, is part of a container, and serves as the cover or seal, usually one that completely closes the object.-History:...

 to a container, etc. There are also special-purpose closing devices, e.g. a bread clip

Bread clip

A bread clip is a device used to hold plastic bags closed. They are also commonly called bread tags, bread tabs, bread ties, bread crimps, bread-bag clips, or bread climps...

. Fasteners used in these manners are often temporary, in that they may be fastened and unfastened repeatedly.

Some types of woodworking joints

Woodworking joints

Joinery is a part of woodworking that involves joining together pieces of wood, to create furniture, structures, toys, and other items. Some wood joints employ fasteners, bindings, or adhesives, while others use only wood elements. The characteristics of wooden joints - strength, flexibility,...

 make use of separate internal reinforcements, such as dowels or biscuits, which in a sense can be considered fasteners within the scope of the joint system, although on their own they are not general purpose fasteners.

Furniture supplied in flat-pack form often uses cam dowels locked by cam locks, also known as conformat fasteners.

Items like a rope

Rope

A rope is a length of fibres, twisted or braided together to improve strength for pulling and connecting. It has tensile strength but is too flexible to provide compressive strength...

, string, wire

Wire

A wire is a single, usually cylindrical, flexible strand or rod of metal. Wires are used to bear mechanical loads and to carry electricity and telecommunications signals. Wire is commonly formed by drawing the metal through a hole in a die or draw plate. Standard sizes are determined by various...

 (e.g.