While Tolkien created numerous languages for his world, Westron was the most widely spoken language in Middle-earth by the Third Age. It was a language of trade and diplomacy, and even the Elves eventually adopted it as a common tongue.
The Hobbits were known for their fondness of their own dialect, often using a more archaic form of Westron, and sometimes including elements of their own unique language, Hobbit-tongue.
It's important to note that while Westron was a spoken language, Tolkien never explicitly defined a written form for it. However, he did create a writing system known as the Common Script, which was used by various peoples of Middle-earth, including the Hobbits.