'Letters' in the Bible

Since Ahab had 70 sons in Samaria, Jehu wrote letters and sent them to Samaria to the rulers of Jezreel, to the elders, and to the guardians of Ahab’s sons, saying:

At that time Merodach-baladan son of Baladan, king of Babylon, sent letters and a gift to Hezekiah since he heard that he had been sick.