The poetry of Gaius Valerius Catullus was written towards the end of the Roman Republic. It describes the lifestyle of the poet and his friends, as well as, most famously, his love for the woman he calls Lesbia.
 Catullus's poems have been preserved in three manuscripts that were copied from one of two copies made from a lost manuscript discovered around 1300. These three surviving manuscript copies are stored at the Bibliothèque Nationale in Paris, the Bodleian Library at Oxford, and the Vatican Library in Rome.  These manuscripts contained approximately 116 of Catullus's carmina. However, a few fragments quoted by later Roman editors but not found in the manuscripts show that there are some additional poems that have been lost. There is no scholarly consensus on whether Catullus himself arranged the order of the poems.
 While the numbering of the poems up to 116 has been retained, three of these poems—18, 19 and 20—are excluded from most modern editions because they are now considered not to be Catullan, having been added by Muretus in his 1554 edition (which identified 113 poems existing in the Catullan manuscripts). Some modern editors (and commentators),  however, retain Poem 18 as genuine Catullan. Furthermore, some editors have considered that, in some cases, two poems have been brought together by previous editors, and, by dividing these, add 2B, 14B, 58B, 68B and 78B as separate poems. Not all editors agree with these divisions, especially with regard to Poem 68.
 
Catullus's carmina can be divided into three formal parts: short poems in varying metres, called polymetra (1–60); eight longer poems (61–68); and forty-eight epigrams (69–116). The longer poems differ from the polymetra and the epigrams not only in length but also in their subjects: there are seven hymns and one mini-epic, or epyllion, the most highly prized form for the "new poets".  The polymetra and the epigrams can be divided into four major thematic groups (ignoring a rather large number of poems eluding such categorization):
 All these poems describe the lifestyle of Catullus and his friends, who, despite Catullus's temporary political post in Bithynia, appear to have lived withdrawn from politics. They were interested mainly in poetry and love. Above all other qualities, Catullus seems to have sought venustas (attractiveness, beauty) and lepos (charm).  The ancient Roman concept of virtus (i.e. of virtue that had to be proved by a political or military career), which Cicero suggested as the solution to the societal problems of the late Republic, are interrogated in Catullus.
 But it is not the traditional notions Catullus rejects, merely their monopolized application to the active life of politics and war. Indeed, he tries to reinvent these notions from a personal point of view and to introduce them into human relationships. For example, he applies the word fides, which traditionally meant faithfulness towards one's political allies, to his relationship with Lesbia and reinterprets it as unconditional faithfulness in love. So, despite the seeming frivolity of his lifestyle, Catullus measured himself and his friends by quite ambitious standards.
 Catullus is the predecessor in Roman elegy for poets like Propertius, Tibullus, and Ovid. Catullus's focus in his poetry is on himself, the male lover. He writes obsessively about Lesbia; however she is just an object to him. In his writing, the male lover is the important character, and Lesbia is part of his theatrical passion. Catullus's love-poetry offers a superb example of why it is not enough in love to focus exclusively on one's own feelings. It is important to note Catullus came at the beginning of this genre, so his work is much different than his predecessors. Ovid is heavily influenced by Catullus; however, he switches the focus of his writing to the concept of love and Amor, rather than himself or the male lover. This opposing views begin to shape the different types of love and controversies in Roman elegiac poetry.
  Catullus deeply admired Sappho and Callimachus.  Poem 66 is a quite faithful translation of Callimachus' poem Βερενίκης Πλόκαμος ("Berenice's Braid", Aetia fr. 110 Pfeiffer) and he adapted one of his epigrams, on the lover Callignotus who broke his promise to Ionis in favor of a boy (Ep. 11 Gow-Page) into poem 70. Poem 51, on the other hand, is an adaption and re-imagining of Sappho 31. Poems 51 and 11 are the only poems of Catullus written in the meter of Sapphic strophe, and may be respectively his first and last poems to Lesbia.   He was also inspired by the corruption of Julius Caesar, Pompey, and the other aristocrats of his time. 
 Catullus was a popular poet in the Renaissance and a central model for the neo-Latin love elegy. By 1347 Petrarch was an admirer and imitator who read the ancient poet in the Verona codex (the "V" manuscript). Catullus also influenced other humanist poets, including Panormita, Pontano, and Marullus.
 Catullus influenced many English poets, including Andrew Marvell and Robert Herrick. Ben Jonson and Christopher Marlowe wrote imitations of his shorter poems, particularly Catullus 5, and John Milton wrote of the poet's "Satyirical sharpness, or naked plainness."
 He has been praised as a lyricist and translated by writers including Thomas Campion, William Wordsworth, James Methven, and Louis Zukofsky.
 Poems 5, 8, 32, 41, 51, 58, 70, 73, 75, 85, 87 and 109 were set to music by Carl Orff as part of his Catulli Carmina.
 Catullus wrote in many different meters including hendecasyllabic and elegiac couplets (common in love poetry). A portion of his poetry (roughly a fourth) shows strong and occasionally wild emotions especially in regard to Lesbia. He also demonstrates a great sense of humour such as in Catullus 13 and 42.
 Many of the literary techniques he used are still common today, including hyperbole: plenus sacculus est aranearum (Catullus 13), which translates as ‘[my] purse is all full – of cobwebs.’ He also uses anaphora e.g. Salve, nec minimo puella naso nec bello pede nec…(Catullus 43) as well as tricolon and alliteration. He is also very fond of diminutives such as in Catullus 50: Hesterno, Licini, die otiose/multum lusimus in meis tabellis – Yesterday, Licinius, was a day of leisure/ playing many games in my little note books.
 Far more than for major Classical poets such as Virgil and Horace, the texts of Catullus's poems are in a corrupted condition, with omissions and disputable word choices present in many of the poems, making textual analysis and even conjectural changes important in the study of his poems.
 A single book of poems by Catullus barely survived the millennia, and the texts of a great many of the poems are considered corrupted to one extent or another from hand transmission of manuscript to manuscript. Even an early scribe, of the manuscript G, lamented the poor condition of the source and announced to readers that he was not to blame:
 You, reader, whoever you are to whose hands this book may find its way, grant pardon to the scribe if you think it corrupt. For he transcribed it from an exemplar which was itself very corrupt. Indeed, there was nothing else available, from which he could have the opportunity of copying this book; and in order to assemble something from this rough and ready source, he decided that it was better to have it in a corrupt state than not to have it at all, while hoping still to be able to correct it from another copy which might happen to emerge. Fare you well, if you do not curse him. Even in the twentieth century, not all major manuscripts were known to all major scholars (or at least the importance of all of the major manuscripts was not recognized), and some important scholarly works on Catullus don't refer to them.
 In the Middle Ages, Catullus appears to have been barely known. In one of the few references to his poetry, Isidore of Seville quotes from the poet in the seventh century. In 966 Bishop Rather of Verona, the poet's hometown, discovered a manuscript of his poems "and reproached himself for spending day and night with Catullus's poetry." No more information on any Catullus manuscript is known again until about 1300.
 A small number of manuscripts were the main vehicles for preserving Catullus's poems, known by these capital-letter names. Other, minor source manuscripts are designated with lower-case letters.
 In summary, these are the relationships of major Catullus manuscripts:
 The text was first printed in Venice by printer Wendelin von Speyer in 1472. There were many manuscripts in circulation by this time. A second printed edition appeared the following year in Parma by Francesco Puteolano, who stated that he had made extensive corrections to the previous edition.
 Over the next hundred years, Poliziano, Scaliger and other humanists worked on the text and "dramatically improved" it, according to Stephen J. Harrison: "the apparatus criticus of any modern edition bears eloquent witness to the activities of these fifteenth and sixteenth-century scholars."
 The divisions of poems gradually approached something very close to the modern divisions, especially with the 1577 edition of Joseph J. Scaliger, Catulli Properti Tibulli nova editio (Paris).
 In 1876, Emil Baehrens brought out the first version of his edition, Catulli Veronensis Liber (two volumes; Leipzig), which contained the text from G and O alone, with a number of emendations.
 The 1949 Oxford Classical Text by R.A.B. Mynors, partly because of its wide availability, has become the standard text, at least in the English-speaking world.
 One very influential article in Catullus scholarship, R.G.M. Nisbet's "Notes on the text and interpretation of Catullus" (available in Nisbet's Collected Papers on Latin Literature, Oxford, 1995), gave Nisbet's own conjectural solutions to more than 20 problematic passages of the poems. He also revived a number of older conjectures, going as far back as Renaissance scholarship, which editors had ignored.
 Another influential text of Catullus poems is that of George P. Goold, Catullus (London, 1983).