Little is known for certain of his life. He was a
friend of Pliny the Younger and married the daughter of Gnaeus Julius
Agricola. In AD97 he was appointed substitute consul under Nerva, and
later he was proconsul of Asia.
The ﬁrst of his works was the Dialogus [dialogue], a discussion of oratory in the style of Cicero, demonstrating to some degree why Tacitus was celebrated as an eloquent speaker; this work was long disputed, but his authorship is now generally accepted. Tacitus then wrote a biography of Agricola, expressing his admiration for his father-in-law as a good and able man.
His small treatise De Origine et situ Germanorum [concerning the origin and location of the Germans] supplies (along with the earlier account of Julius Caesar) the principal written material on the Germanic tribes. Archaeology bears out the accuracy of Tacitus, but the work is not objective; it is a picture of the simple Germans gloriﬁed by comparison with the corruption and luxurious immorality of the Romans.
This moral purpose and severe criticism of contemporary Rome, fallen from the vigour of the old republic, also underlies his two long works, commonly called in English the Histories (of which four books and part of a ﬁfth survive) and the Annals (of which twelve books - Books I-VI, XI-XVI — survive).
The extant books of the Histories cover only the reign of Galba (AD 68-69) and the beginning (to AD70) of the reign of Vespasian but give a thorough view of Roman life — persons, places and events. The surviving books of the Annals tell of the reign of Tiberius, of the last years of Claudius, and of the ﬁrst years of Nero. The account contains incisive character sketches, ironic passages, and eloquent moral conclusions. The declamatory writing of the Dialogus is replaced in the historical works by a polished and highly individual style, a wide range of vocabulary, and an intricate and startling syntax.