How to switch words in an easy manner (in VIM)?

I don't remember where I originally got this, but it's been in my ~/.vimrc for at least a few years:

" Swap the word the cursor is on with the next word (which can be on a
" newline, and punctuation is "skipped"):
nmap <silent> gw "_yiw:s/\(\%#\w\+\)\(\_W\+\)\(\w\+\)/\3\2\1/<CR><C-o>:noh<CR>

After you have this defined, all you need to do is put your cursor somewhere on "param1" in normal mode and type: gw

+1 for @Heptite's answer.

For more completeness, here is what I have in my .vimrc:

" push current line up or down
nnoremap <leader><Up> ddkP
nnoremap <leader><Down> ddp

" exchange character under cursor with the next character without moving the cursor
nnoremap gc xph

" exchange word under cursor with the next word without moving the cursor
nnoremap gw "_yiw:s/\(\%#\w\+\)\(\_W\+\)\(\w\+\)/\3\2\1/<CR><C-o><C-l>

" push word under cursor to the left
nnoremap <leader><Left> "_yiw?\w\+\_W\+\%#<CR>:s/\(\%#\w\+\)\(\_W\+\)\(\w\+\)/\3\2\1/<CR><C-o><C-l>

" push word under cursor to the right
nnoremap <leader><Right> "_yiw:s/\(\%#\w\+\)\(\_W\+\)\(\w\+\)/\3\2\1/<CR><C-o>/\w\+\_W\+<CR><C-l>

Source: the vim wiki.

I see my (and the wiki's) gw is slightly different from Heptite's one. I'm not sure which one is better.

That long solution is ugly. Suppose your cursor is at the left the first letter of the first word, that is 'p'. Do this: dwlpldw%p. This fits in your special case. How about dealing with daily editing? Try dwwP, or dWWP. :D

Tips: Don't always write long regular expression, if you don't need to do this often. Otherwise your vimrc booms. All vim users shall be familiar with its builtin cursor movement.