What is a server mod in the context of Call of Duty?

1. I know what a game mod is. But what is a server mod? Do clients need to install the server mod to get the features of that server mod?

   Also, if I have a mod for a game installed on my computer, and I play the multiplayer version of that game, will I be able to enjoy that mod's features if the server doesn't have that mod installed?

2. If I have many mods installed for my game, how will the game know which one to use? Won't there be a conflict?

Clientmod: A clientmod is a simply modification which mostly just affect the look of your game or the gameplay (without any unfair advantages!). So this could be a texturemod or just some different soundfiles or something.

Servermod: A servermod is needed to manipulate the game in a significant way. So there are servers which kick a player who didn't use a specific weapon or where you can't use your own classes your created (ref. CoD). Instead the servermodded lobby offers you some predesigned classes to achieve a specific kind of gameplay on this server. Servermods can also be little modifications like changed soundfiles (UT-Sounds in CS for example). Besides that there are servermods/tools which make it easier to administrate the gameserver, but I won't call this a mod, it's more an admintool.

Keep in mind that:

• some kind of mods are treated as cheating and may cause you to get banned
• some servermods require you to install the same mod on your client (some mods are downloading and installing them itself as you join a modded server)
• some mods may cause problems in different combinations. Read the manual of the mod for mor information
• if a mod needs the servermodification, then you need to play on a server with this mod installed to enjoy this mod

It depends on game you are talking about.

For example in Minecraft (multiplayer mode) you have:

• Client mods that help you a bit (mostly interface mods) no need server mod
• Client/Server mods that may heavily modify gameplay and need mod installed on server and on client of the same version (mostly)
• Server mods that improve some server functionality (registration, login, etc.) and doesn't need client side mods

So if you have both-side mod only on your client it just won't work.

Especially for Call of Duty - there are server mods like "Reign of the Undead (zombies)" or "Star Wars Mod: Galactic Warfare" need to be set up on a server and you need to have the same client mod. Often client mod files could be downloaded automatically from server on connect.