Czech is attested in documents from the 11th century (isolated Czech words in Latin context), the earliest literary relics date back to the 12th century. In the 14th century we can already speak of a vigorous expansion of literary Czech. At that time its use was not limited only to monasteries and the clergy, but it had spread to the royal court, among nobility, and finally among townsmen. It was employed in religious and secular poetry, in prose and even in philosophy; it was used in law and administration. In the second half of the 14th century the translation of the Bible was completed, and a dictionary in verse was written (by Claretus), summing up Czech terminology of all the fields of study.

In the early 15th century literary Czech spread among broader strata of the population (together with the spread of the Bible). Due to the reformist Hussite movement it drew closer to the spoken language, e.g. in the sermons of John Huss, the ideological leader of the movement, himself (burnt at the stake in 1415); Huss is also considered the author of an important reform of Czech spelling (which will be dealt with below). Literary Czech reached its climax in the 16th and 17th centuries. The world-famous pedagogue J.A. Komenský (Comenius) wrote not only in Latin but also in Czech. However, from the late 17th century Czech was gradually being ousted from a number of communicative domains (e.g. from that of administration), developing mostly as a colloquial language spoken by common people. Literary Czech became destabilised, and in the Czech Lands the influence of German was growing. Fortunately, the unfavourable conditions for the development of Czech were changed during the so-called National Revival in the first half of the 19th century. It was of major importance that the protagonists of this movement (especially the linguist J. Dobrovský, and the lexicographer J. Jungmann) considered the then colloquial language so neglected that they decided to draw on the tradition of the highly developed Czech of the 16th century. Literary Czech and spoken Czech (i.e. the Czech actually used in everyday life) were thus drawn further apart and this gave rise to Czech diglossia, i.e. the functioning of literary Czech (or Standard Czech - put in the current terminology) as a superior code which has no native speakers, and spoken common Czech (or Common Czech) as a lower code, a mother tongue of practically all speakers - today's speakers of Czech are still faced with certain aspects of diglossia (this will be discussed below).