Types of Keychains
– Plastic keyrings
Metal keyrings
– Wooden keyrings
– Keychains with rotating ends
– Keychains with retractable chains

Use of Keychains
– Common souvenir and advertising items
– Promote businesses by displaying name, contact info, and logo
– Three-dimensional plastic keychains became popular in the 1950s and 1960s
– National companies use keychains as promotional items
– Keychains can hold additional functions like army knives, bottle openers, etc.

– Invented by Samuel Harrison in the 19th century
– Most common form is a double loop of metal
– Keyrings can be made of leather, wood, or rubber
– Novelty carabiners are also used as keyrings
– Key fobs are often attached to keyrings for self-identification

Key Fob
– Decorative and functional item carried with keys
– Provides better grip and tactile identification
– Can be a small tool like a flashlight or calculator
– Some key fobs are connected to online services
– Retail establishments use large key fobs to deter theft

Access Control Key Fobs
– Used for controlling access to buildings or vehicles
– Activate remote keyless entry systems in cars
– Early electric key fobs operated using infrared
– More recent models use challenge-response authentication over radio frequency
– Key fobs are used in apartment and condominium buildings for access control

Additional Information:
– Costs of keychains vary depending on the type and purpose.
– Keychains can be collected and displayed in various ways.
– The largest collection of keychains consists of 62,257 items.
– Keychains are also used in computer software for storing cryptographic keys.
– Key finders are related to keychains.
– References are provided for further reading.Sources: