USER MODE i

Usage: UMODE +|-i
Usage: MODE <nick> +|-i
i - Invisible
Makes a user invisible, you will not be able to see what channels this user has joined unless you are in that channel with the user. Most people set themselves +i to avoid being randomly spammed or followed into channels.
The mode also hides your idle and connect times from other users, which otherwise would be shown in the WHOIS info.
Privilege: user
Examples:
/mode jimmers +i
/umode +i

USER MODE I

Usage: UMODE +|-I
Usage: MODE <nick> +|-I
I - Invite block
Blocks all invitations issued with INVITE
Privilege: user
Examples:
/mode jimmers +I
/umode +I