Riddle: I travel the world but stay in a corner. What am I?

Riddle

i-start-with-a-circle-a-triangle-i-become-then-i-am

Riddle

i-am-a-number-sequence-that-begins-with-0-and-1-and-i

Riddle

i-begin-with-a-pair-yet-add-one-more-then-suddenly-im

Riddle

what-appears-once-in-every-minute-twice-in-every-moment

Riddle

i-fly-without-wings-i-cry-without-eyes-whenever-i-go