If you're interested, I wrote an answer on the specifics of regulation of the Venetian Glassmarking industry awhile back which crosses over with a lot of the information I’ll share below. You can read that here.

How glassmaking in Venice first began is pretty up in the air. An outpost of the Eastern Empire long after the disappearance of the Empire in the West, Venetians were in a much better condition to build on Roman and Byzantine traditions of glassmaking compared to much of Western Europe. But there's no real decisive start date, only vague speculation as to where glassmakers might have emigrated from: Venice is one of the few Italian cities not to boast a significant roman past, so early glassmakers must have come from somewhere. Aquileia is sometimes postulated as the potential place of origination for Venetian glassmakers, but there's a pretty big gap between the decline of Aquileia and the presence of glass in Venice, so it's more likely that Venetian glass actually has its origins in the Byzantine (or broader Eastern Mediterranean) tradition. At any rate, archeological evidence dates glass in the Venetian lagoon to the 8th century, and the earliest (sparse) documentary evidence of glassmaking is dated to the 10th.

Venetian cultural and artistic tradition bridging east and west combined with the sustained prosperity of the city in the medieval period created the conditions for a glassmaking industry to develop and grow. The isolation and safety of the city, which famously contributed to make it a favorite stopping-point for mediterranean merchants, also encouraged expensive capital investments, and this included things like glassmaking furnaces. The city's mercantile vocation also allowed for easy sourcing of exotic raw materials and chemicals for the glassmaking process. Last but not least, rivers feeding the lagoon also provided a ready supply of sand. The lagoon itself also provided a ready source of water to extinguish dangerous fires which could spread from glassmaking furnaces, and indeed the the lagoon's geography is what allowed Venetian authorities to eventually decree that all glassmakers move to the island of Murano, on the one hand allowing the industry to grow without threatening the city's center with destructive fires, and on the other hand fostering a tight community of skilled workshops and workers both competing with each other and exchanging ideas and innovations. Lastly, the propensity of Italian artisanal communities to diligently self-regulate via orders and guilds also strengthened the glassmaking community in Murano by creating norms and regulations that everyone could be expected to follow, much in the same way that comparable setups helped Venice and other Italian cities develop serious advantages in the artisanal economy (as an aside, Venice is kind of interesting in that there is a significant two-way dialogue between guilds and government authorities when developing rules for artisanal activity which were codified as a part of venetian law, with glassmaking no exception; this was fairly unique, as in the rest of Italy mercantile regulations were instead pretty much entirely entrusted to guilds wth a neat separation between guild rules and the city's law).

The glassmakers of Murano were also some of the world's earliest successful marketers. Even as other glassmaking centers developed in Europe, glassmaking workshops of Murano were able sustain continuous interest in their work, and their “marques” became serious status symbols. In part, the Venetian mercantile class' pan-european reach (as well as the revolving door of visitors the city played host to) introduced a large number of people in Europe to venetian glasswork, and Venice’s status as Italy’s largest and most prosperous city added to the prestige and desirability of goods coming from the lagoon. And if demand from abroad could ebb and flow as fashions changed and rival glassmaking centers emerged (and as Venice’s importance was eclipsed starting from the 16th century) Venetian society itself was always more than happy to patronize the glassblowers, as wealthy Venetians never abandoned their ​habit of purchasing large collections of both functional and decorative glassware. However, the industry did perceptibly decline in both quantity and quality of output in the last century of the Republic’s life, with the number master glassmakers of international fame declining significantly (in the low single digits) and at the close of the 19th century the industry might have been dealt a deathly blow as the city was subjected to its first foreign occupation, serious political turbulence, and depopulation over the course of the Napoleonic conquest and subsequent annexation to the Austrian Empire. But after the unification of Italy, a new role for the city brought new investments and revitalized the glassmaking industry, preventing it from becoming a historical anecdote and guaranteeing its survival into the modern era. It’s interesting to consider that other high value-added industries where Venetians had been European leaders, such as textiles and fashion, or book publishing, did not experience the sort of revitalization which glassmaking enjoyed.

I'll discuss the modern revitalization of Murano's glassmaking industry in the second part, below.