Both wootz steel and pattern-welded steel are called "Damascus steel", but despite the superficial decorative features they are quite different. Unlike pattern-welded steel, whose pattern arises from the deliberate combination of different metals (iron alloys) during the making of a blade, wootz is a single type of steel that includes various impurities. The esthetic result is similar: waves and circular patterns of light and dark steel.
The term Wootz appears for the first time in print 1795 in the Pearson'Lecture to the Royal Academy on Indian Steel (Hadfield, 1931). The ingots were produced in South India and central India, Hyderabad region (at origin of the ore) and Sri Lanka.
Wootz steel is the result of a complex process of smelting and forging, with varied ingredients used in the crucible stage. Mechanical manipulation of the steel (bending, twisting, folding) in the forging process resulted in a variety of patterns that today we call "wootz". The patterns are hidden until an acid treatment reveals the grain of the steel. Sometimes wootz is referred to as "Damascus steel", for Damascus, Syria where wootz ingots (cakes) were transformed into the swords encountered by Europenas. Wootz ingots were produced in India and exported to Persia (Iran) through the Qajar period. Swords from Persia made from this steel had a legendary reputation in the region and were highly sought after by many, including Arabs, the Turks and also Europeans.
The process of making wootz is conservatively estimated to have originatied in south India in roughly 400 to 500 B.C.E. This most famous of the "True" Damascus was used to make steel weapons through the 7th C. C.E. After that, smiths in Damascus, Toledo and probably some other areas had the knowledge to produce this high-carbon steel themselves. Wootz Damascus blades possessing the highest-quality damascene patterns were produced in the 16th-17th century. The art of making the blades has been lost and today there are only theories about how it was produced and why it possessed such striking visual and metalurgical properties.
Wootz steel contains an abundance of ultahard metallic carbides. This endows blades made from the steel with sharpness as well as toughness (the ability to keep and edge, resist breakage). See: The Key Role of Impurities in Ancient Damascus Steel Blades, by J.D. Verhoeven, A.H. Pendray, and W.E. Dauksch