Command Line Interface (CLI) commands

One line command or what?

I'm not sure how to do the following instruction (searched and searched and searched but could not find an answer):

$ sudo ./letsencrypt-auto certonly \
--webroot --webroot-path /var/www/htdocs/ \
--email admin@example.com \
-d www.example.com

Must I write each line and press enter after each \ ?

Or must I write one space after \ to make it one long command, like this:
$ sudo ./letsencrypt-auto certonly \ --webroot --webroot-path /var/www/htdocs/ \ --email admin@example.com \ -d www.example.com

Thanks