Basic Usage⌗

  • delete inside parentheses (which can be replaced with any symbol)
    • di(
    • di"
    • di'
    • …

Split⌗

  • Horizontal: ctrl + w + s
  • Vertical: ctrl + w + v

Replace a word with yanked text⌗

yiw               Yank inner word (copy word under cursor, say "first").
                  Move the cursor to another word (say "second").
ciw Ctrl-R 0 Esc  Change "second", replacing it with "first". (Ctrl-R: paste `0` register in insert mode)
                  Move the cursor to another word (say "third").
.                 Repeat the operation (change word and replace it with "first").
                  Move the cursor to another word and press . to repeat the change.
      
ref: https://vim.fandom.com/wiki/Replace_a_word_with_yanked_text