Open A Tag In A Split Window

Using tags and ctrl-] is a quick way to jump from the use of a keyword to the declaration or definition whether in the same file or another file. Sometimes what you really want is that tag definition opened up in a (horizontal) split window. That way you can see the definition without losing context. This can be accomplished with ctrl-w ].

The Vim help file gives the following definition of this command:

Use identifier under cursor as a tag and jump to it in the new upper window.

See :h CTRL-W_] for more details.

h/t Dorian Karter