I know there is probably a simple explanation to this but for some reason I just can't seem to wrap my head around it and it's bothering me.

Kion vi faras? <-- Why exactly is it necessary to add the "n" to Kio?

Kio vi faras? <-- Is this not saying the same thing?

I keep going back to my grammar rules and remembering that you add an "n" to the direct object of a sentence. Is the "n" being added because the "what" is what is being done?

Oi... >.<

Vdoutherd:Is the "n" being added because the "what" is what is being done?

Yes, exactly. (Jes, precize).

You gave the answer to yourself already

The direct object in Esperanto receives (if possible, e.g. nouns or words like "kio" ) an "n" to mark it as the object. Look at these sentences:

Li ŝatas hundojn. - He likes dogs.
Kion li ŝatas? - What does he like?

In this example you can clearly recognize the subject (li), verb (ŝatas) and object (hundojn, kion). "Kion" asks for the object that he likes (hundojn), so an "n" is put to it to mark it.

See this example:

Kion vi faras? - What do you do?
Mi legas. - I am reading.

Although there is nothing with an "n" in the sentence "mi legas", there is an "n" at the end of "kion", because the thing that I do (reading) is the "object" I am asked about.

I understand that it is not quite easy for native English speakers to get used to the accusative "n", because there is no such marker in your native tongue. Well, almost none, if you look at these examples:

You see me. - Vi vidas min. (You couldn't say "You see I", you have to say "me" to mark it as the object.)

Who(m) do you see? - Kiun vi vidas? ("Whom" is a good example of an object marker (for the direct or indirect object) that is put to the end of the word "who" just like you do it in Esperanto, although it seems to "wear off" over time and is rarely used nowadays, as far as I know as a German speaker.)

Many people have asked the question: Why do we need to mark the object, if we can recognize it by word order: "I like dogs." subject - predicate - object

The answer is: freedom Freedom in placing words in your sentences.

Mi ŝatas hundojn. - I like dogs.
Hundojn ŝatas mi. = Hundojn mi ŝatas. - (It's) dogs I like. (not "dogs like I", which would be "hundoj kiel mi" )

If you want to show that you like especially dogs, just put it in front of your Esperanto sentence. It remains. In English you have to rebuild the sentence in a completely different way (It's dogs I like) to be understood. Or look at

Dogs like me. - Hundoj ŝatas min *or* Hundoj kiel mi

So the "n" is a very useful thing in Esperanto. One thing left to say is that it can not be put to every word, e.g.

Mi ŝatas legi. - I like to read.

In this sentence "legi" acts as the object, but it doesn't have an "n", because it's an infinitive, and as such it can not be given the "n". Or proper names often don't get an "n":

Mi vidis William. - I saw William.

It is clear that "William" is the one being seen (the object), because "mi" doesn't have an "n", so it must be the subject. (compare "Min vidis William." - "William saw me." )

Espereble mi ne skribis tro multe

Salutas
Markus

Ok. I see now. Thank you both very much. I don't know why that was so hard for me to grasp. ^_^
I appreciate the help!
Dankon!

pohli:Many people have asked the question: Why do we need to mark the object, if we can recognize it by word order: "I like dogs." subject - predicate - object

The answer is: freedom Freedom in placing words in your sentences.

Great answer Markus. There is another reason that Esperanto uses the 'n' accusative... not all languages use the same word order as in English. Turkish, Latin, Russian, Japanese... I think German (but you'll have to ask Markus about that one!), are different. I suppose Zamenhof had that in mind developing an 'International' language.

By the way Vdoutherd, I am also a beginner so if you want to chat with a non-expert let me know!