/Mode \<channel\> [[+|-]|o|p|s|i|t|n|b|v] [\<limit\>] [\<user\>] [\<ban mask\>]
/Mode \<nickname\> [[+|-]|i|w|s|o]
*
/Mode changes mode for a user or a channel. The possibilities are limited by your own mode (notably whether you are operator or not).
For users:
i	makes the user invisible
s	makes the user receive server notices
w	makes the user receive wallops
o	makes the user an operator
 
For channels:
o	give/take channel operator privileges
p	private channel flag
s	secret channel flag
i	invite-only channel flag
t	topic settable by channel operator only flag
n	no messages to channel from clients on the outside
m	moderated channel
l	set the user limit on channel
b	set a ban mask to keep users out
v	give/take the ability to speak on a moderated channel
k	set a channel key (password)
*
/Mode #acorn +i
*
would change #acorn to be invite-only.
