Q:

Edit multiple files without splitting window

I am new to VIM.
It seems like, in order for copy and paste functionality to work between different files, one must open the files in the same VIM instance. Doing this, however, splits the terminal screen into 2. Opening a new file, splits it into 3, etc.
what happens if i have to open, say, 10+ files? how do developers who use VIM deal with this issue?

A:

You can open files in the same vim instance and in the same window (without spliting it). That's what is called buffers. The view you see is current buffer, but the others buffers are still opened.
Here you have an introduction on how to work in vim with buffers.
Or type :help buffers in vim.
You can use some plugin to work more user friendly with vim buffers. I recommend you bufexplorer or minibufexpl.
You can as well use tabs, but I have been always more confortable with buffers, but it's just my case.

A:

Use tabedit instead of split to open more files.

A:

Most users use splits only for simultaneous viewing of two files, when it is needed. You can open as many files as you want in different buffers, while only displaying one buffer on screen.
:e File1.txt
:e File2.txt and so on ...

and then switch through buffers with :bprevious and :bnext (and a variety of other commands). That is really the Vim's way of work.
There are many plugins for manipulating and navigating buffers.
One tab per file is really the wrong way to go ...

