A librarian is a person who works professionally in a library providing access to information, and sometimes social or technical programming, or instruction on information literacy to users. The role of the librarian has changed much over time, with the past century in particular bringing many new media and technologies into play. From the earliest libraries in the ancient world to the modern information hub, there have been keepers and disseminators of the information held in data stores. Roles and responsibilities vary widely depending on the type of library, the specialty of the librarian, and the functions needed to maintain collections and make them available to its users. Education for librarianship has changed over time to reflect changing roles. History The ancient world The Sumerians were the first to train clerks to keep records of accounts. "Masters of the books" or "keepers of the tablets" were scribes or priests who were trained to handle the vast amount and complexity of these records. The extent of their specific duties is unknown. Sometime in the 8th century BC, Ashurbanipal, King of Assyria, created a library at his palace in Nineveh in Mesopotamia. Ashurbanipal was the first individual in history to introduce librarianship as a profession. We know of at least one "keeper of the books" who was employed to oversee the thousands of tablets on Sumerian and Babylonian materials, including literary texts; history; omens; astronomical calculations; mathematical tables; grammatical and linguistic tables; dictionaries; and commercial records and laws. All of these tablets were cataloged and arranged in logical order by subject or type, each having an identification tag. The Great Library of Alexandria, created by Ptolemy I after the death of Alexander the Great in 323 BC, was created to house the entirety of Greek literature. It was notable for its famous librarians: Demetrius, Zenodotus, Eratosthenes, Apollonius, Aristophanes, Aristarchus, and Callimachus. These scholars contributed significantly to the collection and cataloging of the wide variety of scrolls in the library's collection. Most notably, Callimachus created what is considered to be the first subject catalog of the library holdings, called the pinakes. The pinakes contained 120 scrolls arranged into ten subject classes; each class was then subdivided, listing authors alphabetically by titles. The librarians at Alexandria were considered the "custodians of learning". Near the end of the Roman Republic and the beginning of the Roman Empire, it was common for Roman aristocrats to hold