Numbers are a common invention of mankind. At least in the classical Greek times, the success story of mathematics, geometry, and number theory began. While many persons made single more or less important contributions, there are few names which stand for rapid and comprehensive accurate developments. In this short history, the progress of number theory is described and neither the history of single persons, which are standing for a time, school, or university, nor the history of mathematics or geometry. The designation "number theory" is used here for all what is connected with understanding and use of numbers.In 12 chapters, after an introduction, secret numbers, pre-Greek mathematics, Greek and Hellenistic number theory, Indian, Chinese, and Mayan contributions, the Greek Heritage in the two Roman empires, the Arabian language area, the time of translations, new ideas (about 1500 untiI1700), the great time of number theory (about 1700 until 1900), the ramification of number theory in the 20th century, and languages and numerals are discussed.