i - inserts before cursor
I - insert at start of line
a - insert after cursor
A - insert at end of line
o - add new line below cursor (open a new line)
O - add new line above cursor
Esc or Ctrl+[ - exit insert mode
10i - insert 10 items of similar text before cursor
3I - text is prefixed 3 times to the line or block
3A - text is suffixed 3 times to the line or block
3o - 3 lines will be added below current line
3O - 3 lines will be added above current line
Insert key - same as i