Wire-strung instruments have had a long history of use in music-making, even if not quite as long as their gut-strung counterparts. They have been valued over the centuries for providing a timbre unattainable with gut and were frequently included as a vital component in mixed consorts.
The ability to draw metal into wire was a technological innovation far advanced from the cleaning, splitting, and twisting of animals’ intestines. It was an innovation that also took time to develop. Archaeological digs show that the Vikings may have been making metal wire over a thousand years ago, but evidence of the use of wire in musical instruments comes from about the 12th century onward. For several centuries afterward, the use of wire for strings seems to have been used primarily in non-fretted instruments, possibly because the technology for making the strings true enough for use in fretted instruments had not yet been perfected.
During the middle of the 16th century, we have the first evidence of the creation of twisted strings (also known as "twined" or "wreathed" strings)––a technology in which a single strand of wire is twisted onto itself in such a way that it creates a form of tight double-helix. The purpose for this string type is to create a string that will function better in the bass range of instruments. Due to the uniform nature of a monofilament strand of wire, thicker gauges become increasingly inelastic, preventing the string from rendering an accurate note when fretted. The twisted string instead reproduces the mass of a thicker gauge of wire (allowing it to be tuned to a lower pitch) but retains flexibility (for accurate fretting), much like multiple strands of wire in a cable allow the cable to be flexible. It was probably not until the end of the 17th century that another solution––the practice of winding a wire around a core of gut, silk, or metal (i.e. "covered" or "wound" strings)––became common.
Twisted strings offer to the modern musician an early but effective solution for the problem of increasing string mass without negatively affecting flexibility. They have the added advantage of being closer than wound strings to monofilament strings in sound and sustain, being somewhat less elastic than modern wound strings. Also, as there is no "core" (since both strands of the string are twisted around each other), there are no windings to come loose, as in wound strings. This, coupled with the ability to create nearly any gauge imaginable through the interaction of strand diameter and twist ratio, makes a string that is ideal for performers of period instruments who desire an historically appropriate string and the ability to customize their stringing choices to suit both their taste and style.