Proto-Semitic is the hypothetical common ancestor of all Semitic languages, which include languages like Hebrew, Arabic, and Amharic. Linguists reconstruct Proto-Semitic by comparing similarities among these languages, allowing them to infer features of the original language spoken thousands of years ago. This ancient language is believed to have been spoken around 4,000 to 3,000 BCE in the region of the Middle East. Proto-Semitic is characterized by a system of consonantal roots, which form the basis for word formation in its descendant languages. Understanding Proto-Semitic helps linguists trace the evolution of Semitic languages over time.