Power Bracelet

The Power Bracelet is a strength-increasing item that bolsters Link's muscular power to that of a superhuman, or it's equivalent in the Zelda universe, a Goron, for the most part. Power Bracelet, as a blanket term, not only caters to the physical ring-like objects Link acquires throughout his travels, but also defines the strength-intensifying gloves and mitts, such as the Golden Gauntlet and the Titan's Mitt, that allow Link to perform at an increased strength level as well. The actual bracelet is more common in the 2D Zelda games but has also made appearances in The Wind Waker; their glove-like counterparts appear vividly in Ocarina of Time and A Link to the Past, respectively.

Power Bracelet(s)
The Power Bracelet is not only the most rudimentary of the strength-inducing items, as it appeared first in the original The Legend of Zelda, but is also the most popular of the two, the other being its identical counterpart, the Power Glove. Since its first appearance in The Legend of Zelda, the Power Bracelet is a gold ring-like object (save for its burgundy Link's Awakening incarnation) that is obtained through significant plot events, whether it is given to help in  ridding the Dodongo's Cavern of baddies in Ocarina  of Time (this version is called the Goron's Bracelet), required to access  the Earth Temple in The Wind  Waker, or simply needed to uplift small boulders in titles such as The Legend of Zelda and The Minish Cap, the latter of which can only be used while Link is Minish-size.

Although they are mostly called Power Bracelets, they very rarely exist in pairs, appearing only as such in The Wind Waker and The Minish Cap. Regardless of the number of bracelets, the effect on Link is the same - he is able to lift otherwise unliftable objects ranging from mere rocks and bookcases in The Legend of Zelda and The Minish Cap to large, Stone Heads in The Wind Waker.

Interestingly, the Power Bracelet of Link's Awakening can be upgraded to a Level 2 over the course of Link's journey, enabling him to lift even  heavier objects than before, and the iteration used in Four Swords Adventures is the only incarnation of Power Bracelet that can be used, lost, and regained between levels, as the bracelet only appears in levels that require its specific use. The iteration seen in Oracle of Ages bridges the gap between Power Bracelets and Power Gloves, as the bracelet can be upgraded to the superior glove version before accessing the Ancient Tomb, a dungeon that requires the extra strength provided in the Power Glove to complete.

Power Gloves, Titan's Mitt, and the Gauntlets
The Power Glove is a minor twist on the Power Bracelet, however, the increased strength effect is practically identical to that of its ring-like counterpart. Appearing originally in The Adventure of Link, its most primordial function operates through Link's sword: it increases the strength of the sword itself, so much so that it can slice and crush blocks. Over subsequent titles, beginning with A Link to the Past and on through Ocarina of Time, such emphasis is placed instead on Link's physical strength, stemming from his hands and his ability to lift objects in comparison to slicing them, when speaking of the Power Glove. The glove of A Link to the Past can even be upgraded from its original form to the Titan's Mitt, a superior, golden glove that can lift heavier, dark boulders; the obtainment the Titan's Mitt further spurs Link towards achieving the Tempered Sword, as well.

The Power Glove truly did not achieve its current popularity until it broke into the third dimension, in the forms of the Silver and Gold Gauntlets seen exclusively in Ocarina  of Time. These metallic gloves, obtained in the Spirit Temple, were the behemoths of the strength-inducing objects, as they retained the ability to lift monoliths of extreme size, often many times the height of Link, just with the flick of the wrist. While these gauntlets could only be used in Link's adult era, they play a huge role in the game's plot, alleviating blocked passageways, revealing secret Great Fairy Fountains, and the Golden Gauntlets even came in handy inside Ganon's Tower, aiding in the completion of both Light and Fire rooms. Not only can the Golden Gauntlets lift towering black blocks in comparison to the lesser Silver version, they replace the Silver Gauntlets and the Goron's  Bracelet (only usable by the younger Link) in Link's inventory upon its obtainment.

Trivia

 * In Master Quest, the Golden Gauntlets have relocated from the Shadow Room to the Spirit Room.
 * Curiously, the Power Bracelets don't seem to affect Link's strength at normal size, in The Minish Cap.
 * The power glove may be a reference to the power glove controller for the NES.