The Republic of Venice, officially the Most Serene Republic of Venice and traditionally known as La Serenissima, was a sovereign state and maritime republic with its capital in Venice. Founded, according to tradition, in 697 by Paolo Lucio Anafesto, over the course of its 1,100 years of history it established itself as one of the major European commercial and naval powers. Initially extended in the Dogado area (a territory currently comparable to the Metropolitan City of Venice), during its history it annexed a large part of Northeast Italy, Istria, Dalmatia, the coasts of present-day Montenegro and Albania as well as numerous islands in the Adriatic and eastern Ionian seas. At the height of its expansion, between the 13th and 16th centuries, it also governed Crete, Cyprus, the Peloponnese, a number of Greek islands, as well as several cities and ports in the eastern Mediterranean.

The islands of the Venetian Lagoon in the 7th century, after having experienced a period of substantial increase in population, were organized into Maritime Venice, a Byzantine duchy dependent on the Exarchate of Ravenna. With the fall of the Exarchate and the weakening of Byzantine power, the Duchy of Venice arose, led by a doge and established on the island of Rialto; it prospered from maritime trade with the Byzantine Empire and other eastern states. To safeguard the trade routes, between the 9th and 11th centuries the Duchy waged several wars, which ensured its complete dominion over the Adriatic. Owing to its participation in the Crusades, Venice increasingly penetrated into eastern markets and, between the 12th and 13th centuries, managed to extend its power into numerous eastern emporiums and commercial ports. The supremacy over the Mediterranean Sea led the Republic to the clash with Genoa, which lasted until the 14th century, when, after having risked complete collapse during the War of Chioggia (with the Genoese army and fleet in the lagoon for a long period), Venice quickly managed to recover from the territorial losses suffered with the Treaty of Turin of 1381 and begin expansion on the mainland.

Venetian expansion, however, led to the coalition of the Habsburg monarchy, Spain and France in the League of Cambrai, which in 1509 defeated the Republic of Venice in the Battle of Agnadello. While maintaining most of its mainland possessions, Venice was defeated, and the attempt to expand the eastern dominions caused a long series of wars against the Ottoman Empire, which ended only in the 18th century with the Treaty of Passarowitz of 1718 and which caused the loss of all possessions in the Aegean. Although still a thriving cultural centre, the Republic of Venice was occupied by Napoleon's French troops and its territories were divided with the Habsburg monarchy following the ratification of the Treaty of Campo Formio.

Throughout its history, the Republic of Venice was characterized by its political order. Inherited from the previous Byzantine administrative structures, its head of state was the doge, a position which became elective from the end of the 9th century. In addition to the doge, the administration of the Republic was directed by various assemblies: the Great Council, with legislative functions, which was supported by the Minor Council, the Council of Forty and the Council of Ten, responsible for judicial matters, and the Senate.

During its long history, the Republic of Venice took on various names, all closely linked to the titles attributed to the doge. During the 8th century, when Venice still depended on the Byzantine Empire, the doge was called in Latin Dux Venetiarum Provinciae ('Doge of the Province of Venice'), and then, starting from 840, Dux Veneticorum ('Doge of the Venetians'), following the signing of the Pactum Lotharii. This commercial agreement between the Duchy of Venice (Ducatum Venetiae) and the Carolingian Empire de facto ratified the independence of Venice from the Byzantine Empire.

In the following century, references to Venice as a Byzantine dominion disappeared, and in a document from 976 there is a mention of the most glorious Domino Venetiarum ('Lord of Venice'), where the 'most glorious' appellative had already been used for the first time in the Pactum Lotharii and where the appellative "lord" refers to the fact that the doge was still considered like a king, even if elected by the popular assembly. Gaining independence, Venice also began to expand on the coasts of the Adriatic Sea, and so starting from 1109, following the conquest of Dalmatia and the Croatian coast, the doge formally received the title of Venetiae Dalmatiae atque Chroatiae Dux ('Doge of Venice, Dalmatia and Croatia'), a name that continued to be used until the 18th century. Starting from the 15th century, the documents written in Latin were joined by those in the Venetian language, and in parallel with the events in Italy, the Duchy of Venice also changed its name, becoming the Lordship of Venice, which as written in the peace treaty of 1453 with Sultan Mehmed II was fully named the Illustrissima et Excellentissima deta Signoria de Venexia ('The Most Illustrious and Excellent Signoria of Venice').

During the 17th century, monarchical absolutism was made in many countries of continental Europe, radically changing the European political landscape. This change made it possible to more markedly determine the differences between monarchies and republics: while the former had economies governed by strict laws and dominated by agriculture, the latter lived off of commercial affairs and free markets. Moreover, the monarchies, in addition to being led by a single ruling family, were more prone to war and religious uniformity. This increasingly noticeable difference between monarchy and republic began to be specified also in official documents, and it was hence that names such as the Republic of Genoa or the Republic of the Seven United Provinces were born. The Lordship of Venice also adapted to this new terminology, becoming the Most Serene Republic of Venice (Italian: Serenissima Repubblica di Venezia; Venetian: Serenìsima Repùblega de Venexia), a name by which it is best known today. Similarly, the doge was also given the nickname of serenissimo or more simply that of His Serenity. From the 17th century the Republic of Venice took on other more or less official names such as the Venetian State or the Venetian Republic. The republic is often referred to as La Serenissima, in reference to its title as one of the "Most Serene Republics".

The Duchy of Venice was born in the 9th century from the Byzantine territories of Maritime Venice. According to tradition, the first doge was elected in 697, but this figure is of dubious historicity and comparable to that of the exarch Paul, who, similarly to the doge, was assassinated in 727 following a revolt. Father Pietro Antonio of Venetia, in his history of the lagoon city published in 1688, writes: "The precise time in which that family arrived in the Adria is not found, but rather, what already an inhabitant of the islands, by the princes, who welcomed citizens, and supported with the advantage of significant riches, in the year 697 she contributed to the nomination of the first Prince Marco Contarini, one of the 22 Tribunes of the Islands, who made the election". In 726, Emperor Leo III attempted to extend iconoclasm to the Exarchate of Ravenna, causing numerous revolts throughout the territory. In reaction to the reform, the local populations appointed several duces to replace the Byzantine governors and in particular Venetia appointed Orso as its doge, who governed the lagoon for a decade. Following his death, the Byzantines entrusted the government of the province to the regime of the magistri militum, which lasted until 742 when the emperor granted the people the appointment of a dux. The Venetians elected by acclamation Theodato, son of Orso, who decided to move the capital of the duchy from Heraclia to Metamauco.