I have been using IRC for many years and I think its hard for most new users
to understand all these "modes" what they are and how to set them.
So to avoid people spamming me on irc with questions I desided to write this to help new and more advanced users along.

Contents:
Intro
Channel modes
User modes
Additional info


Intro(Top)

On irc you can set modes, these can be compaired with settings for a channel or user.
Channel modes can be set by typing:
/mode #channel <the modes> <additional info>
User modes can be set by typing:
/mode <user> <the modes> <additional info>
Infront of the modes you put + to add them and - to remove them
Example: /mode #help +o weekend
Multiple modes can be set on a single user or channel at the same time by combining them.
Example: /mode #help +oa-v weekend weekend weekend
A mode will stay set untill it gets unset.

Most modes can only be set by someone who has some other modes set.
Example: Setting channel mode +o (operator) can only be done by someone who himself has +o, +a, +q or by an irc operator.

In this article I will simply list just about every single mode used on unrealircd based off the list provided by the server. This article should mainly be used to lookup modes when needed and possibly find out about usefull modes you didn't know about. At the end i will give more details about modes that are a litle harder to understand.
If anyone thinks some of the other modes need more explaining then let me know and i will eddit it


Channel modes(Top)

Channel modes always affect a channel in some way.
They affect who gets to set modes, limits what users get to say on the channel and what they get to do (example: limit users from joining) or something else.

Channel access(Channel modes)(Top)
These modes basically define what access you have on a channel.
Someone with one of these modes set helps maintain the channel and removes disruptive users. (except for +v that's used if +m is set or is just a status symbol if it isn't)

v <nickname> = Gives Voice to the user (May talk if chan is +m)
h <nickname> = Gives HalfOp status to the user (Limited op access)
o <nickname> = Gives Operator status to the user
a <nickname> = Gives Channel Admin to the user
q <nickname> = Gives Owner status to the user

Message Filter(Channel modes)(Top)
These modes affect what is allowed to get said and possibly by who.

c = Block messages containing mIRC color codes [need atleast +o to set]
f <floodparams> = Flood protection (see below for more info) [need atleast +o to set]
m = Moderated channel (only +vhoaq users may speak) [need atleast +h to set]
n = Users outside the channel can not send PRIVMSGs to the channel [need atleast +h to set]
C = No CTCPs allowed in the channel [need atleast +o to set]
G = Filters out all Bad words in messages with <censored> [need atleast +o to set]
M = Must be using a registered nick (+r), or have a voice (+v) to talk [need atleast +o to set]
S = Strips mIRC color codes [need atleast +o to set]

Limiting commands(Channel modes)(Top)
These modes limit what commands users can use. Limiting if they can join, change nick etc etc

b <nick!ident@host> = Bans the nick!ident@host from the channel (see below for more info) [need atleast +h to set]
e <nick!ident@host> = Overrides a ban for matching users (see below for more info) [need atleast +h to set]
I <nick!ident@host> = Overrides +i for matching users [need atleast +h to set]
i = A user must be invited to join the channel [need atleast +h to set]
j <joins:sec> = Throttle joins per-user to 'joins' per 'sec' seconds [need atleast +o to set]
k <key> = Users must specify <key> to join [need atleast +h to set]
l <number of max users> = Channel may hold at most <number> of users [need atleast +o to set]
t = Only +hoaq may change the topic [need atleast +h to set]
z = Only Clients on a Secure Connection (SSL) can join [need atleast +o to set]
A = Server/Net Admin only channel (settable by Admins)
K = /KNOCK is not allowed [need atleast +o to set]
N = No Nickname changes are permitted in the channel [need atleast +o to set]
O = IRC Operator only channel (settable by IRCops)
Q = No kicks allowed [need atleast +o to set]
R = Only registered (+r) users may join the channel [need atleast +o to set]
T = No NOTICEs allowed in the channel [need atleast +o to set]
V = /INVITE is not allowed [need atleast +o to set]

Other(Channel modes)(Top)

r = The channel is registered (settable by services only)
p = Private channel [need atleast +o to set]
s = Secret channel [need atleast +o to set]
L <chan2> = Channel link (If +l is full, the next user will auto-join <chan2>) [need atleast +q to set]
u = Auditorium mode (/names and /who #channel only show channel ops) [need atleast +q to set]


User modes(Top)

User modes are used to hide/show information, limit people from contacting you and give special privileges to users.

Information(User modes)(Top)
These modes show/hide information about you to other people or shows/hides information from you.

g = Can read and send to GlobOps, and LocOps
h = Available for Help (Help Operator)
i = Invisible (Not shown in /WHO searches)
p = Hide all channels in /whois and /who
r = Identifies the nick as being Registered (settable by services only)
s = Can listen to Server notices
t = Says that you are using a /VHOST
v = Receive infected DCC send rejection notices
w = Can listen to Wallop messages
x = Gives the user Hidden Hostname (security)
z = Marks the client as being on a Secure Connection (SSL)
H = Hide IRCop status in /WHO and /WHOIS. (IRC Operators only)
V = Marks the client as a WebTV user
W = Lets you see when people do a /WHOIS on you (IRC Operators only)
B = Marks you as being a Bot

Limitations(User modes)(Top)
These modes limit people from interacting with you.

d = Makes it so you can not receive channel PRIVMSGs (Deaf)
q = Only U:lines can kick you (Services Admins/Net Admins only)
G = Filters out all Bad words in your messages with <censored>
R = Allows you to only receive PRIVMSGs/NOTICEs from registered (+r) users
T = Prevents you from receiving CTCPs

Special privileges(User modes)(Top)
These modes grant you special privileges on the server.

O = Local IRC Operator
o = Global IRC Operator
C = Is a Co Administrator
A = Is a Server Administrator
a = Is a Services Administrator
N = Is a Network Administrator
(see below for more info)

S = For Services only. (Protects them)


Additional info(Top)


Channel mode +f(Additional info)(Top)

An example of the use of this mode:
/mode #channel +f [10j]:15
- in this example j is the type of protection(only 10 joins every 15 seconds alowed)
you can set several at a time by using a , to seperate them, example:
/mode #channel +f [5j,10t]:15
- 5 joins and 10 lines of text alowed every 15 seconds

you can set c, j, k, m, n and t

c: limits the amound of ctcp's send: will set +C when someone sends more then alowed
- other available actions m,M use: /mode #channel +f [5c#m]:15
j: limits the amount of joins: will set +i when someone sends more then alowed
- other available action R use: /mode #channel +f [5j#R]:15 (sets +R only registered users can join)
k: limit amount of knocks (users will knock to get let ops kno they want to get invited): will set +K
m: limit amount of messages/notices: will set +m
- other available action M use: /mode #channel +f [5m#M]:15
n: limited amount of nickchanges: will set +N
t: limited amount of text (messages or notices): will kick the user
- other available action b use: /mode #channel +f [5t#b]:15 (will ban the user)

Extended bantypes(Additional info)(Top)

You can use extended bantypes with +b and +e
+b is used to ban a user from a channel and +e to set an exempt on the bans set in the channel.
Extended bans look like ~<type>:<stuff>

There is ~q, ~n, ~c and ~r

~q stands for quiet, anyone matching this ban can join and change nick but can not speak unless they have +v or higher.
Example: ~q:*!cows@the.farm

~n stands for nick, if you match this ban then you can talk and join but you cannot change nick unless you have +v or higher.
Example: ~n:*!cows@the.farm

~c stands for channel, if the user is in this channel then (s)he is unable to join.
with this extended bantype you can specify a prefix (+, %, @, & or ~) alowing you to only block people with those rights or higher on the specified channel.
+ = +v, % = +h, @ = +o, & = +a, ~ = +q
Example:
~c:#monkeys
~c:+#monkeys
The last one would only block someone with +v or higher on #monkeys this can easily be evaded but since these extended bantypes also work with +e you could block everyone from a certain channel except the ops.
Example:
+be ~c:#monkeys ~c:@monkeys

~r stands for realname, if the realname of a user matches this then (s)he is unable to join.
Example: ~r:*monkey_face*
An underscore '_' matches both a space and an underscore.

IRC Operators(Additional info)(Top)

An IRC Operator is someone who helps maintain the server and has more access then the average user.
An IRC Operator needs to login using the /oper command.

Each oper will have a bunch of flags set which give him certain abilities on the server.
I will list all flags below.

Note: these flags are not the same as modes Example: the mode O (caps) would set the flag o (no caps).

Old Flag = New Flag = Description
o = Local = Mmakes you a local operator
O = global = makes you a global operator
C = Coadmin = makes you a coadmin
A = admin = makes you an admin
a = services-admin = makes you a services admin
N = netadmin = makes you a network admin
r = can_rehash = Oper may use /rehash
D = can_die = Oper may use /die
R = can_restart = Oper may use /restart
h = helpop = Oper receives umode +h (helpop)
w = can_wallops = Oper can send /wallops
g = can_globops = Oper can send /globops
c = can_localroute = can connect servers locally
L = can_globalroute = Can connect servers globally
k = Can_localkill = can /kill local users
K = can_globalkill = can /kill global users
b = can_kline = can use /kline
B = can_unkline = can use /kline -user@host
n = can_localnotice = can send local server notices
G = can_globalnotice = can send global server notices
z = can_zline = can use /zline
t = can_gkline = can use /gline, /shun and /spamfilter
Z = can_gzline = can use /gzline
W = get_umodew = sets umode +W when u oper
H = get_host = sets your host to an oper host
v = can_override = can use operoverride
q = can_setq = can set usermode +q
X = can_addline = can use /addline
d = can_dccdeny = can use /dccdeny and /undccdeny

Some flags will automaticly set other flags.

setting Local will set: rhgwckbBn
setting Global will set: rhgwckbBnLKG
setting admin/coadmin will set: rhgwckbBnLKGOd
setting services-admin will set: rhgwckbBnLKGOdq
setting netadmin will set: rhgwckbBnLKGOdqAa


--writen by weekend, contact me on irc if it needs to be edited. (like more info on some mode)