Daig (/daɪɡ/) is an expression common in Basel and the rest of German-speaking Switzerland and refers to a milieu consisting of wealthy families from the city,

These primarily Protestant families had full civic rights in the then city-state since the High Middle Ages and are known for their particular idiosyncratic habits and a dialect distinct from that of the rest of the population. For centuries the Daig was the social, political and economic elite of Basel, becoming a quasi city aristocracy, although always remaining judicially part of the bourgeois class.

While Daig literally means 'dough' in Swiss German, it is most likely that the name is derived from the Middle High German word deig, a term denoting a moat in front of a rampart. This is further supported by the similarity to the Greek τεĩχος ('wall') or the word Deich, which has come to signify 'dike' in contemporary German. During the early Middle Ages, the social standing of inhabitants was reflected by whether they lived on the lower levels of the city in the vicinity of the Rhine, or on the slopes of either the 'Münsterhügel' (cathedral hill) or the 'Spalenberg' hill. Living on a hillside not only conveyed the family's high social standing, the hillsides were also the only parts of the city that provided inhabitants with a constant supply of fresh water, which was routed there at the time from springs higher up on the hill via primitive wooden aqueducts.

While the 'Münsterhügel' was home to clerics and the seat of the prince-bishop, the 'Spalenberg' was inhabited by knights and other nobility, tasked with defending the city. While the location of the knight's quarters was in line with the overall social topography of the city at the time, the primary reasons for the location was undoubtedly a strategic one, as it was in the direct vicinity of the 11th-century city walls, nowadays known as 'Burckhardtsche Stadtmauer'. With the city's knights and their liegemen living right next to the city's defenses, they were able to man the ramparts within minutes in the case of an unexpected attack on the city. Thus the term 'Daig' when used to refer to the city's noblemen literally meant 'those that live at and man the city walls.'

Since the late Middle Ages the Bürgerschaft commoners who enjoyed civic rights, most of whom were artisans and members of one of the city's powerful guilds, had successively acquired most regalia from Basel's official ruler, the Prince-Bishop of Basel, such as the Münzregal, the right to impose tariffs, and eventually even the right to low jurisdiction, which allowed the commoners to institute their own courts except for such crimes that were punishable by death; only they had to be decided by a court of so-called high justice (see Blutgerichtsbarkeit).

With the prince-bishop bereft of most of his customary privileges and powers, Basel became de facto independent and was ruled by a city council dominated by the city's ever powerful guilds. However, it was not until 1500 that the townsmen were finally able to get rid of their feudal ruler, forcing him to move his residence out of Basel, which enabled the city to join the Eidgenossenschaft as its 11th canton. The canton then encompassed not merely the city but significant territory in its vicinity that had been acquired, and Basel was still a feudal bishopric. The former residences of knights and other noblemen that had left with the Prince-Bishop were largely acquired by wealthy families, in some cases noble themselves, that over time became a quasi city aristocracy. Along with the estates of the noblemen, these families also inherited the name Daig that eventually came to be associated with these new inhabitants.

While citizens from both the city and the surrounding municipalities of the countryside were represented in the 'Grand Council,' i.e. the cantonal parliament, the latter was dominated by the city, despite having a smaller population than the combined municipalities of the countryside. At the turn of the 19th century this caused growing discontent among the 'Baselbieter' (the citizens of the surrounding municipalities), escalating into armed conflict between Basel and the 'Baselbiet' in 1830. After initial victories for the city it was eventually defeated in 1833.

The medieval Tagsatzung, at the time still the highest national authority in Switzerland (and the only one), mandated a separation of the canton, with the city merely retaining the municipalities of Riehen, Bettingen and Kleinhüningen, which would have otherwise become enclaves surrounded by the city of Basel. These developments caused great resentment in Basel, especially among Basel's ruling elite, which fostered antipathy towards all citizens of the newly-formed canton of Basel-Landschaft as well as 'outsiders' in general. Over time, that sentiment contributed in shaping the distinct mentality characteristic of the Daig milieu.