You need to learn about registers. You can copy between windows and even use your OS's clipboard via Vim. Normally y is used to yank. However, you can prefix i

You need to learn about registers. You can copy between windows and even use your OS's clipboard via Vim. Normally y is used to yank. However, you can prefix it with "x to yank in to register x. Then you can "xp to paste from register x. You have registers 0-9 and a-z for regular use. They work within a single window. If you use register *, the register corresponds to your OS clipboard. Read :help registers to learn more.