Bilbo Baggins’s sword in J.R.R. Tolkien’s works is called Sting.
Bilbo finds Sting in a troll hoard alongside two larger Elvish swords, Glamdring and Orcrist. Because it is short enough for a Hobbit to use, Bilbo treats it as a sword even though it resembles a large knife to a Man or Elf. He names it Sting after using it against giant spiders in Mirkwood.
Sting has a distinctive magical property: its blade glows blue when Orcs or Goblins are near. Bilbo uses it during The Hobbit, and later gives it to Frodo. Frodo carries Sting through much of The Lord of the Rings, including the journey through Shelob’s lair.
Sting is often confused with Andúril, Aragorn’s reforged sword, or Glamdring, Gandalf’s blade. Those are separate weapons with different owners and histories.