The county is named for its principal town, which was founded in the ninth century by the Vikings and taken by their collateral descendants the Normans in the twelfth century, in the very early stages of their invasion. They fortified it and gave it much of the character it still has. The eastern part of the county was granted to the Le Poer family, ancestors of the legions of Power families still found in the county, while the western part, formerly the old kingdom of Decies, came under the sway of a branch of the Fitzgeralds. Outside the town, Norman influences were thoroughly absorbed into the old way of life. At Ring, near Dungarvan in the west of the county, is one of the few surviving Irish-speaking areas.
Waterford's strong sea-faring traditions meant that migration was common here long before the nineteenth century. As early as the 1650s there was a settlement from the county in Newfoundland, and strong links with Canada, and the particularly its Atlantic provinces of Newfoundland, Nova Scotia and New Brunswick, have continued down to the present.
Waterford was, of course, home of the famous cut crystal-ware.
Some of the surnames most commonly found in the county today include Brazil, Power, Ryan, Duggan, Fennessy, Gough, Tobin, Phelan, Prendergast and Walsh.