Yank (copy)
yw
Yank (copy) word
yy
Yank current line
"
a
yy
Yank current line into named buffer
a
(a-z). Uppercase names append text.
y
motion
Yank text between the cursor and the target of
motion
p, P
Put yanked text after, before cursor
"
a
P
Put text from buffer
a
before cursor (a-z)