What is knitting yarn?

Any kind, but most knitters all agree that wool is best if you can afford it. They also stay far away from most acrylic yarn (i.e Red Heart) but their are some, like microspun. Wool feelsvery nice, and can also be felted, which acrylic cannot. ---- Alpaca is great yarn too. and if you're talking brands that are cheap but nice i suggest "Caron Simply Soft" it is cheap, you can buy it anywhere, even Walmart. It's acrylic but it is very soft and good for everyday projects.