'за' и 'для'

[watsong]

Hello. I have a question on the words 'за' and 'для'.

Both words seem to mean 'For'. What is the difference in usage of these two words?

для тебя
за тебя
Both seem to mean the same.

[russian_guy]

ok this is a good question the difference between the two was confusing for me so i hope i can make this clear to you
за means something like to you or for you but для is something different like when i am searching in russian for a specific something like русский для детей
i hope this helps

[watsong]

So, to clarify, please determine if I am correct with the following sentences:

This is for you. (за)
I booked a taxi for you. (за)
I was searching for a pencil. (для)
I did it for you. (для)
A bicycle is for riding on. (для)
For world peace! (за)
For me? (или Для меня? или За меня?)

[russian_guy]

yes

[ppfeffer]

no....this is incorrect. за is used for "exchanges". Example: I give you $1 FOR this orange. Or: I thank you FOR this. However: "This is for you" would be formed with для. Its not an exchange. Furthermore, "I was searching for a pencil" and some of the other examples you gave would not be translated with either form of FOR. The word FOR is often left out in translation to russian....instead the accusative case or the instrumental is used to communicate what you're trying to say.

[roxanasharie]

"За" doesn't always mean "for". The primary meaning of it is "behind".
Here are the cases when "за" means "for":

1) instead of
Я сделаю это за тебя – I'll do it for you (instead of you)
Сдай за меня экзамен! – Take an exam for me! (instead of me)
2) when you approve or advocate something, favor or like something
Я за честное правительство – I'm for the honest government
3) in consideration or payment of; in return for; in exchange for
Спасибо за помощь – thank you for your help
Я купил телефон за 100 долларов – I bought a phone for 100 dollars
Я за тебя умру – I'll die for you
4) in punishment of
Он ответит за преступление – he'll pay for the crime
5) in toasts (in the meaning of "to")
За тебя! – To you!
За здоровье! – To health!

The meaning and usage of "для":

1) with the object or purpose of
бег полезен для здоровья – Jogging is good for your health
2) intended to belong to; suiting the purposes or needs of
комната для гостей – a room for guests (guest room)
корм для собак – food for dogs (dog food)
3) doing a favor for someone
Я для тебя всё сделаю – I'll do everything for you
(but as ppfeffer has said, "for" can often be left out and expressed through the Case changes: Я тебе приготовила ужин – I cooked dinner for you)

[watsong]

Good clarification, roxanasharie. Thanks.