Franz Kafka was born in Prague, July 3, 1883, the son of Hermann and Julie Kafka. The oldest, he had three surviving younger sisters. Valli, Elli, and Ottla. His father was a self-made middle class Jewish merchant, who raised his children in the hope of assimilating them into the mainstream society of the Austro-Hungarian Empire.
The official ruling language of the empire was German, so Franz attended German grammar school (Volksschule am Fleischmarkt), and later the German Gymnasium (Altstädter Deutsches Gymnasium). He finished his Doctorate of Law in Prague, studying at the German language University (Die deutsche Universität) there. He initially gained employment at a private insurance firm Assicurazioni Generali and then with the Arbeiter-Unfall-Versicherungs-Anstalt für das Königreichs Böhmen in Prag.
Kafka's job at the Worker's Accident Insurance provided him with a steady income and 'regular' office hours, so that he could dedicate his evenings to writing. His diaries contain continuing accounts of his restlessness and sleeplessness, as he would work all night writing, only to return to the office for the next day of work, thoroughly exhausted.
Although he spoke and wrote Czech fluently throughout his life, his literary work was all completed in German. He is known to have started writing at an early age, but all of his earliest attempts were later destroyed. His first published work came in 1907, and he continued to publish throughout the next seventeen years, but most of his works were published posthumously by his friend Max Brod. Kafka's relationship to his father dominates all discussions of both his life and his work. See his Brief and den Vater to get a feel for the relationship between the thin, intellectual, and awkward Franz, and the robust, loud, and military corporal Father. The ideas of 'father' and 'family' permeate the fabric of many of Kafka's texts, either directly as in Das Urteil or Die Verwandlung or more abstractly as in the cases of his two novels The Trial and The Castle (which remained unpublished during his lifetime).
Sources: Jewish Prague by Tom's Travel