A bracelet was a decorative piece of jewelry usually worn around the wrist.
In 2269, Christine Chapel wore a bracelet made by the titanium smiths of Libra. Due to the effects of spiroid epsilon waves, she shrunk sufficiently that it more closely resembled a necklace than an arm bracelet.(TAS: "The Terratin Incident")
The Sirah used a bracelet with a fragment of an orb in its center to control the Dal'Rok. (DS9: "The Storyteller")
Miles O'Brien gave his wife Keiko a gold bracelet while they visited McKinley Park. (TNG: "Power Play")
Young Bajoran girls often received a Bajoran betrothal bracelet to indicate they were "promised" to another for the purposes of marriage at a later date in their adulthood. (DS9: "Fascination")
Prior to heading down to Golana, Molly O'Brien asked her mother to help her put on a bracelet. (DS9: "Time's Orphan")
Some individuals or groups who sought to enslave or coerce others used a control bracelet for the purposes of torture and discipline. (TOS: "Spock's Brain")