abbreviation at the end of your Guild Name

The more I look around I see strange abbeviation next to the players name.
Can somebody explain to me how you can do that? And where you can find the symbols you can use?

The abbreviation at the end of player's name is something called their "Guild tag". This is something you get after you've joined a guild. My guild is called Internet Explorers iE which means that anybody who joins gets the tag iE after their name.

By "strange" do you mean like japanese letters? Those can be made my japanese accounts, many people pay others to have guilds made for them with japanese tags. If that's not what you mean, i'm not sure.

Players from regions that don't use the Latin system of writing are allowed to write their names with a subset of Unicode that contains, e.g., Cyrillic, Chinese, Japanese and Korean characters as well as some additional symbols. All clients support the available subset so that you can write Japanese in your chat box if you know how to do it, but you must be of the proper region to use the related symbols in character or guild names and guild name tags. This has spawned a business opportunity since people from non-Latin regions can create and sell guilds to those Latin region players who want to have a 'cool' guild tag.

check the services offered area of the forums for people who do this for a fee.

you can't use japanese/korean characters unless you have a japanese/korean account. fortunately though, you can ask around in kamadan for a japanese or korean person to make a guild for you.

Yes i have seen trading chats offering to make a chinese, japannesse or even korean guild. But the last couple of weeks i have seen strange symbols just as guild tag. I dont think it is of any launguae.