Answer:
Die without me, never thank me. Walk right through me, never feel me. Always watching, never speaking. Always lurking, never seen.
I drift forever with the current down these long canals they’ve made, Tame, yet wild, I run elusive Multitasking to your aid. Before I came, the world was darker, colder, sometimes, rougher, true. But though I might make living easy, I’m good at killing people too.
I have legs but walk not, a strong back but work not. Two good arms but reach not. A seat but sit and tarry not.
They're up near the sky, on something very tall. Sometimes they die, only then do they fall.
My first is an insect; my second is a border; my whole puts the face in a tuneful disorder.
I’m grown from darkness but shine with a pale light. Very round I am and always a lady's delight.